Epsilon-HNIW particle size regulation and control method based on microfluidic technology

Abstract

The invention discloses a micro-fluidic technology-based epsilon-HNIW particle size regulation and control method, which comprises the following steps: by taking ethyl acetate as a solvent and petroleum ether, n-heptane or n-octane as a non-solvent, adjusting the types of the used solvent and non-solvent and a subsequent treatment method, obtaining three products with different particle sizes under a micro-fluidic preparation system, and respectively obtaining D50 of 2.77 [mu] m (Span: 0.646), 17.22 [mu] m (Span: 0.507) and 50.35 [mu] m (Span: 0.582). The epsilon-HNIW particle size regulation and control method based on the microfluidic technology has the advantages that operation is safe, continuous preparation is achieved, the product particle size is controllable, particle size distribution is narrow, and the product crystal form is epsilon-type.

Description

Technical Field

[0001] The invention belongs to the field of energetic materials and relates to a method for controlling the particle size of ε-HNIW based on microfluidic technology. Background Art

[0002] Hexanitrohexaazaisowurtzitane (HNIW) has four crystal forms at room temperature: α, β, γ and ε. Among them, ε-HNIW has the highest density. Its high detonation velocity and detonation pressure characteristics make it have good application prospects in weapons and equipment. The different particle size grades of ε-HNIW currently used are mostly obtained through molecular sieves, and their particle size distribution is wide and the application performance is poor. In order to improve the application performance of HNIW products and obtain ε-HNIW with a narrow particle size distribution, the preparation of ε-HNIW of different particle sizes can be achieved by recrystallization.

[0003] The refinement of microfluidic recrystallization microreactor technology is essentially the solvent-nonsolvent crystallization method. The difference is that the explosive solution and the nonsolvent are mixed in a fixed ratio in the microreactor, and the crystallization process is in a shear dispersion process, which is conducive to obtaining particles with uniform particle size. Compared with traditional kettle recrystallization technology, microfluidic technology has higher mass transfer, faster heat transfer rate, less reagent dosage and more accurate reaction parameter control. However, how to obtain HNIW products with various particle size levels and ε-crystal form through microfluidic technology remains to be explored. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for controlling the particle size of ε-HNIW based on microfluidic technology, so as to solve the problem that the prior art cannot obtain HNIW products with various particle sizes and ε-crystalline form through microfluidic technology. The method of the present invention successfully prepared D 50 The particle sizes of ε-HNIW are 2.77 μm (Span: 0.646), 17.22 μm (Span: 0.507) and 50.35 μm (Span: 0.582) respectively. The crystal form is ε-type HNIW. This method can use the same set of microfluidic equipment to prepare ε-HNIW of various particle sizes, effectively reducing the preparation cost and improving the safety of the preparation process.

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

[0006] A method for controlling the particle size of ε-HNIW based on microfluidics technology comprises the following steps:

[0007] Step 1, HNIW is completely dissolved in a solvent as a solvent phase, and a non-solvent as a non-solvent phase;

[0008] Step 2, injecting the solvent phase and the non-solvent phase into the recrystallization module respectively, and collecting the suspension after it flows out;

[0009] Step 3, washing the collected suspension with a detergent and drying it to obtain ε-HNIW crystals.

[0010] The present invention also includes the following technical features:

[0011] Specifically, the recrystallization module is a microfluidic chip with a specific structure, including but not limited to a heart-shaped, vortex-shaped, and T-shaped.

[0012] Specifically, the solvent is ethyl acetate; the non-solvent is petroleum ether, n-heptane or n-octane; and the detergent is ethanol.

[0013] Specifically, the concentration of the solvent phase is 0.1-0.3 g / ml, and the flow rate of injection into the recrystallization module is 0.5-1 ml / min;

[0014] The flow rate of the non-solvent phase injected into the recrystallization module is 10-20 ml / min; the flow rate ratio of the solvent phase to the non-solvent phase is 1:10-1:20.

[0015] Specifically, in step 3, the collected suspension is heated at 50° C. for 30 min, washed with ethanol, and freeze-dried for 12 h to obtain ε-HNIW crystals.

[0016] Specifically, in step 3, the collected suspension is stirred for 30 min-1 h, allowed to stand for 4 h-6 h, washed with ethanol, and freeze-dried for 12 h to obtain ε-HNIW crystals.

[0017] Specifically, this method can obtain D 50 ε-HNIW of 2.77μm, 17.22μm and 50.35μm.

[0018] Compared with the prior art, the present invention has the following technical effects:

[0019] (1) The present invention can utilize the same microfluidic preparation system to adjust the process parameters to obtain ε-HNIW products with D50 of 2.77 μm, 17.22 μm, and 50.35 μm, respectively.

[0020] (2) The present invention takes advantage of the microfluidics in preparing micro-nano energetic materials, and the prepared HNIW samples have a narrow particle size distribution and few surface defects.

[0021] (3) The preparation method proposed in the present invention can achieve stable crystal form during product preparation, and the online amount of dangerous goods can be controlled at the milligram level, ensuring the safety of the preparation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 (a) is a SEM photograph and a particle size distribution diagram of the HNIW raw material used in the example; (b) is a SEM photograph and a particle size distribution diagram prepared by Example 1 of the method of the present invention; (c) is a SEM photograph and a particle size distribution diagram prepared by Example 2 of the method of the present invention; (d) is a SEM photograph and a particle size distribution diagram prepared by Example 3 of the method of the present invention.

[0023] Figure 2 The following are the XRD patterns of the HNIW raw material used in the examples, and examples 1, 2 and 3. DETAILED DESCRIPTION

[0024] The present invention provides a method for controlling the particle size of ε-HNIW based on microfluidic technology, specifically a method for preparing hexanitrohexaazaisowurtzitane of different particle sizes based on microfluidic technology. The present invention first selects a suitable ε-HNIW preparation process according to the particle size of the required product, and then mixes the solvent and non-solvent in a recrystallization unit and collects the resulting suspension for treatment. Specifically, a solution is prepared as a solvent phase, petroleum ether, n-heptane or n-octane as a non-solvent phase, and ethanol is used as a detergent; the driving device injects the solvent phase and the non-solvent phase into the recrystallization module at a certain flow rate, and the suspension generated by the precipitation of HNIW crystals is collected after flowing out, washed after treatment, and dried. Specifically including:

[0025] Step 1, HNIW is completely dissolved in a solvent as a solvent phase, and a non-solvent is used as a non-solvent phase; the solvent is ethyl acetate; and the non-solvent is petroleum ether, n-heptane or n-octane.

[0026] Step 2, the driving device injects the solvent phase and the non-solvent phase into the recrystallization module at a certain flow rate respectively, and collects the suspension after it flows out; wherein the recrystallization module is a microfluidic chip with a specific structure, including but not limited to heart-shaped, vortex-shaped, and T-shaped; the solvent phase concentration is 0.1-0.3 g / ml, and the flow rate of injection into the recrystallization module is 0.5-1 ml / min; the flow rate of the non-solvent phase into the recrystallization module is 10-20 ml / min; the flow rate ratio of the solvent phase and the non-solvent phase is 1:10-1:20.

[0027] Step 3, washing the collected suspension with a detergent and drying it to obtain ε-HNIW crystals; specifically, the detergent is ethanol; wherein the collected suspension is heated at 50° C. for 30 min, washed with ethanol, and freeze-dried for 12 h to obtain ε-HNIW crystals; or the collected suspension is stirred for 30 min-1 h, allowed to stand for 4 h-6 h, washed with ethanol, and freeze-dried for 12 h to obtain ε-HNIW crystals.

[0028] This method can obtain D 50The ε-HNIWs are 2.77μm, 17.22μm and 50.35μm; the product has stable crystal form and controllable particle size.

[0029] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0030] Embodiment 1:

[0031] This embodiment provides a method for controlling the particle size of ε-HNIW based on microfluidics technology, comprising:

[0032] Solution preparation: A: weigh 3g HNIW and dissolve it in 10ml ethyl acetate, stir magnetically for 10min; B: 200ml n-octane.

[0033] Sample preparation: Inject solutions A and B into the microfluidic chip through syringe pumps No. 1 and No. 2 at flow rates of 1 ml / min and 20 ml / min, respectively.

[0034] Sample treatment: The collected suspension was heated at 50°C for 30 min, washed with ethanol, and freeze-dried for 12 h to obtain D 50 The ε-HNIW with a particle size of 2.77 μm is shown in the SEM photo and particle size distribution diagram. Figure 1 (b), XRD spectrum see Figure 2 .

[0035] Embodiment 2:

[0036] This embodiment provides a method for controlling the particle size of ε-HNIW based on microfluidics technology, comprising:

[0037] Solution preparation: A: weigh 3 g HNIW and dissolve it in 10 ml ethyl acetate, stir magnetically for 10 min; B: 150 ml n-heptane.

[0038] Sample preparation: Inject solutions A and B into the microfluidic chip through syringe pumps No. 1 and No. 2 at flow rates of 1 ml / min and 15 ml / min, respectively.

[0039] Sample treatment: The collected suspension was stirred for 1 h, allowed to stand for 4 h, washed with ethanol, and freeze-dried for 12 h to obtain D 50 The particle size of ε-HNIW is 17.22 μm. The SEM photo and particle size distribution diagram are shown in Figure 1 (c), XRD spectrum see Figure 2 .

[0040] Embodiment 3:

[0041] This embodiment provides a method for controlling the particle size of ε-HNIW based on microfluidics technology, comprising:

[0042] Solution preparation: A: weigh 3 g HNIW and dissolve it in 10 ml ethyl acetate, stir magnetically for 10 min; B: 200 ml petroleum ether.

[0043] Sample preparation: Inject solutions A and B into the microfluidic chip through syringe pumps No. 1 and No. 2 at flow rates of 1 ml / min and 20 ml / min, respectively.

[0044] Sample treatment: The collected suspension was magnetically stirred for 30 min and then allowed to stand for 6 h, washed with ethanol and freeze-dried for 12 h to obtain D 50 The ε-HNIW with a particle size of 50.35 μm is shown in the SEM photo and particle size distribution diagram. Figure 1 (d), XRD spectrum see Figure 2 .

[0045] Sample characterization analysis:

[0046] Figure 1 (a), (b), (c), and (d) are SEM photos and particle size distribution diagrams of HINW raw materials and ε-HNIW prepared by the method of the present invention, respectively. It can be seen that the raw material particles are uneven in size, irregular in shape, large particles have many sharp edges and many surface defects. In contrast, the particle size of the three particle size ε-HNIW samples prepared by the method of the present invention is significantly reduced, the particle size distribution is narrow, and the surface is smooth. Figure 2 The XRD patterns of the raw materials and three-size ε-HNIW samples show that the crystal forms of the raw materials and the three-size ε-HNIW samples are consistent with the standard materials. The above characterization results reflect that the use of microfluidics can not only effectively improve the morphology and particle size distribution of HNIW, but also ensure that the crystal form of HNIW before and after recrystallization remains consistent. And the SEM results effectively verify that this method can flexibly control the particle size of HNIW, which has practical application value.

[0047] The above discussion is based on the optimal embodiment and does not limit the present invention. The various technical features involved can be freely combined under different processes, and will not be described here one by one. Any technician in this field can adjust the process parameters within the scope of the technical solution based on this system, and its essence still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for controlling the particle size of ε-HNIW based on microfluidics, characterized in that: The following steps are involved: Step 1, HNIW is completely dissolved in a solvent as a solvent phase, and a non-solvent as a non-solvent phase; Step 2, injecting the solvent phase and the non-solvent phase into the recrystallization module respectively, and collecting the suspension after it flows out; Step 3, washing the collected suspension with a detergent and drying it to obtain ε-HNIW crystals.

2. The ε-HNIW particle size control method based on microfluidics technology according to claim 1, characterized in that: The recrystallization module is a microfluidic chip with a specific structure, including but not limited to a heart-shaped, vortex-shaped, and T-shaped.

3. The ε-HNIW particle size control method based on microfluidics technology according to claim 1, characterized in that: The solvent is ethyl acetate; the non-solvent is petroleum ether, n-heptane or n-octane; and the detergent is ethanol.

4. The ε-HNIW particle size control method based on microfluidics technology according to claim 1, characterized in that: The solvent phase concentration is 0.1-0.3 g / ml, and the injection flow rate into the recrystallization module is 0.5-1 ml / min; The flow rate of the non-solvent phase injected into the recrystallization module is 10-20 ml / min; the flow rate ratio of the solvent phase to the non-solvent phase is 1:10-1:

20.

5. The ε-HNIW particle size control method based on microfluidics technology according to claim 1, characterized in that: In the step 3, the collected suspension is heated at 50° C. for 30 min, washed with ethanol, and freeze-dried for 12 h to obtain ε-HNIW crystals.

6. The ε-HNIW particle size control method based on microfluidics technology according to claim 1, characterized in that: In the step 3, the collected suspension is stirred for 30 min-1 h, allowed to stand for 4 h-6 h, washed with ethanol, and freeze-dried for 12 h to obtain ε-HNIW crystals.

7. The ε-HNIW particle size control method based on microfluidics technology according to claim 1, characterized in that: This method can obtain D 50 ε-HNIW of 2.77μm, 17.22μm and 50.35μm.

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