Application of poly (p-phenylenediamine) as nitrate compound stabilizer

Abstract

The invention belongs to the technical field of stabilization of nitrate ester compounds, and particularly relates to application of poly (p-phenylenediamine) as a stabilizer for the nitrate ester compounds, and the addition amount of the poly (p-phenylenediamine) is 2.9%-3.1% on the basis of the total weight of the nitrate ester compounds. The preparation method of the poly (p-phenylenediamine) comprises the following steps: taking ammonium persulfate as an oxidizing agent, taking p-phenylenediamine as a monomer, adopting a spiral gas-solid two-phase flow technology, and enabling raw material solid particles to mutually rub and collide to initiate an oxidative polymerization reaction, so as to prepare the poly (p-phenylenediamine). The poly (p-phenylenediamine) has the characteristics of low price, easiness in synthesis, no toxicity, excellent nitrogen oxide absorption capacity and the like, has good compatibility with nitrate ester compounds, can effectively reduce the autocatalysis phenomenon and improve the long-term stability of the nitrate ester compounds, can avoid the toxicity problem of the traditional amine stabilizer when being used as the stabilizer, and has the advantages of low cost, low cost and the like. The environment and human health are facilitated.

Description

Technical Field

[0001] This invention belongs to the field of nitrate ester compound stabilization technology, specifically relating to the application of poly(p-phenylene diamine) as a stabilizer for nitrate ester compounds. Background Technology

[0002] Nitrate esters (NCs), such as nitrocellulose and nitroglycerin, are widely used in propellants, propellants, missiles, and aerospace due to their high energy density and good combustion performance. However, the nitrate ester functional groups in nitrate esters are unstable and prone to bond breaking, producing nitrogen oxides and acidic substances. These decomposition products have strong autocatalytic properties, accelerating the degradation of nitrate esters through hydrolysis, heat, and other pathways. Under long-term storage and high-temperature conditions, their chemical stability decreases, and they may even cause spontaneous combustion or explosion. To mitigate these risks, stabilizers are usually added. These stabilizers interact chemically or physically with the nitrogen oxides produced by nitrate esters, reducing or inhibiting autocatalysis and thus improving the long-term stability of the material. However, in practical applications of stabilizers, traditional aliphatic amines and aromatic amines, due to the highly reactive amino groups in their molecular structures, readily undergo nitrosation reactions with the nitrous acid produced by the decomposition of nitrate esters, generating highly carcinogenic nitrosamine byproducts. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides the application of poly(p-phenylenediamine) as a stabilizer for nitrate ester compounds.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The application of poly(p-phenylenediamine) as a stabilizer for nitrate ester compounds is based on the total weight of the nitrate ester compounds, wherein the amount of poly(p-phenylenediamine) added is 2.9% to 3.1%.

[0005] Furthermore, the preparation steps of poly(p-phenylene diamine) are as follows: Using p-phenylenediamine as a monomer and ammonium persulfate as an oxidant, a spiral gas-solid two-phase flow technology was adopted. Under the action of high-speed airflow, the raw material solid particles rub and collide with each other to initiate an oxidative polymerization reaction, thus producing poly(p-phenylenediamine).

[0006] In the preparation of poly(p-phenylene diamine), under the action of a spiral airflow field, the raw material solid particles are driven by the high-speed airflow to rub and collide with each other at high speed, converting mechanical energy into activation energy required for the chemical reaction. This promotes the breaking and recombination of intermolecular covalent bonds in the solid-phase reaction, thereby obtaining poly(p-phenylene diamine) through an oxidative polymerization reaction under solvent-free conditions. Compared with traditional chemical synthesis methods, the solid-phase reaction method provided by this invention relies on mechanical force to promote direct contact and activation between particles, and has the advantages of being green and environmentally friendly, and reducing the use of solvents.

[0007] Furthermore, the preparation of poly(p-phenylene diamine) is carried out in a spiral gas-solid two-phase flow reactor.

[0008] Furthermore, the spiral gas-solid two-phase flow reactor includes a reaction chamber top cover and a housing, with the top cover and housing closed to form a sealed reaction chamber. A ring of reaction chamber walls is fixed inside the housing, dividing the reaction chamber into an outer ring reaction chamber and an inner ring reaction chamber. A feed pipe, a carrier gas inlet pipe, and a gas outlet pipe are fixed on the top cover of the reaction chamber. The feed pipe connects to the inner ring reaction chamber and carries the raw material powder into the inner ring reaction chamber via the sample gas. The carrier gas inlet pipe connects to the outer ring reaction chamber and is used to introduce carrier gas. Multiple nozzles offset from the radial direction are provided on the reaction chamber shell wall. The carrier gas in the outer ring reaction chamber enters the inner ring reaction chamber through these nozzles, forming a spiral airflow that drives the raw material powder to rub and collide with each other, initiating an oxidative polymerization reaction. A connecting port is provided at the center of the inner ring reaction chamber. The connecting port is coaxial with the gas outlet pipe, and there is a gap between the connecting port and the gas outlet pipe, allowing the gas after the oxidative polymerization reaction to be discharged through the gas outlet pipe, and the product particles to be discharged through the connecting port.

[0009] Furthermore, each nozzle deviates from the radial direction by an angle of 30° to 45°, preferably 30°, and is arranged in a counterclockwise or clockwise direction.

[0010] Furthermore, to maximize yield and efficiency, the optimal molar ratio of ammonium persulfate to p-phenylenediamine is 1:1 to 2.

[0011] Furthermore, to maximize productivity and efficiency, the optimal inlet pressure for high-speed airflow is 0.5 MPa to 1.1 MPa.

[0012] Furthermore, the particle size of poly(p-phenylene diamine) is 0.17 μm to 0.29 μm.

[0013] The application of poly(p-phenylene diamine) as a stabilizer for nitrate ester compounds: Poly(p-phenylene diamine) has a similar structure to the traditional stabilizer diphenylamine and can capture and absorb nitrogen oxides.

[0014] Furthermore, the nitrate ester compound is nitrocellulose or nitroglycerin.

[0015] Based on the total weight of nitrate ester compounds, the amount of poly(p-phenylene diamine) added is 2.9% to 3.1%. When the content of poly(p-phenylene diamine) is low, it cannot play a stabilizing role, and when the content is high, it will reduce the energy performance of the energetic material and thus increase the production cost.

[0016] This invention employs a spiral gas-solid two-phase flow reactor. By adjusting the parameters of the gas delivery unit, the gas pressure entering the supersonic nozzle is adjusted, and a spiral gas flow field is generated in the reaction chamber by introducing carrier gas. Ammonium persulfate and p-phenylenediamine are then used as raw materials, mixed evenly, and fed through a feeder. Under the action of high-speed gas flow, the solid particles of the reactants rub and collide with each other, initiating an oxidative polymerization reaction. This invention utilizes air jet mill technology, effectively avoiding the problems of material adhesion and blockage in the reaction chamber, ensuring the stable operation of the continuous preparation process. The self-grading function formed by the spiral gas flow field allows for real-time and continuous separation of the generated fine particulate products from the reaction chamber, thus constructing a highly efficient continuous production process. The poly(p-phenylenediamine) produced using the above process, when used as a stabilizer, can significantly improve the stability of nitrate ester compounds.

[0017] The poly(p-phenylene diamine) stabilizer provided by this invention is characterized by its low cost, ease of synthesis, non-toxicity, and excellent nitrogen oxide absorption capacity. It has good compatibility with nitrate ester compounds, effectively reduces autocatalysis, improves the long-term stability of nitrate ester compounds, and reduces the risk of thermal runaway and hazard. When used as a stabilizer, it avoids the toxicity problems of traditional amine stabilizers, which is more beneficial to the environment and human health. Moreover, the preparation process is simple and can achieve solvent-free continuous mechanochemical synthesis, showing good application prospects.

[0018] This invention utilizes the self-grading function of a spiral flow field to achieve continuous production; it avoids material adhesion and blockage in the reaction chamber, ensuring the effective execution of the continuous preparation process. The self-grading function generated by the spiral airflow field can continuously and promptly separate the generated fine particulate products from the reaction chamber, transforming the traditional chemical production process into a continuous production process, achieving continuous and efficient synthesis. Specifically, it shortens the reaction time of materials to less than 1 minute, which is several times faster than traditional chemical methods, effectively improving the preparation efficiency.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses the application of poly(p-phenylene diamine) as a stabilizer for nitrate ester compounds. Based on the total weight of the nitrate ester compounds, the amount of poly(p-phenylene diamine) added is 2.9%–3.1%. When poly(p-phenylene diamine) is used as a stabilizer in this invention, the nitrosation reaction between the amino group and nitrous acid is not involved. The core reason is that its molecular structure and mechanism of action fundamentally avoid the conditions for this reaction. On the one hand, the amino group (-NH2) in traditional aliphatic amine and aromatic amine stabilizers is in a free state and has extremely high reactivity, easily reacting with nitrous acid produced from the decomposition of nitrate esters to form nitrosamines. While the poly(p-phenylene diamine) of this invention contains an amino group, the amino group is tightly bound to the benzene ring through polymerization, forming a stable conjugated structure. The reactivity of the amino group is significantly reduced, and it no longer possesses the high reactivity conditions for nitrosation reaction with nitrous acid, structurally blocking the initiation of this reaction. On the other hand, the role of poly(p-phenylene diamine) and the decomposition products of nitrate esters in this invention revolves solely around the capture and conversion of nitrogen oxides (such as NO2), specifically the conversion of NO2 to NO2 under acidic conditions. + NO2 + As an electrophile, it attacks the benzene ring of poly(p-phenylene diamine), and through a conjugated electrophilic aromatic nitration reaction, forms a positively charged intermediate, which is eventually converted into nitrobenzene; at the same time, H + It activates NO2 molecules and forms π-complexes with the benzene ring, further promoting the binding of NO2 with the benzene ring and transferring nitrobenzene. Throughout the process, the amino group of poly(p-phenylene diamine) does not participate in any reaction with nitrous acid, and does not involve the nitrosation reaction pathway of amino group with nitrous acid in traditional stabilizers. It does not generate nitrosamine byproducts, effectively avoiding the toxicity problems of traditional amine stabilizers, and is more beneficial to the environment and human health.

[0020] This invention employs a spiral gas-solid two-phase flow mechanochemical synthesis method to prepare poly(p-phenylene diamine). This synthesis method is superior to traditional chemical synthesis methods, offering faster synthesis speed, higher yield, simpler and more efficient preparation process, and solvent-free synthesis pathway. It is an environmentally friendly synthesis method suitable for large-scale preparation. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a structural diagram of a spiral gas-solid two-phase flow reactor.

[0023] Figure 2 This is a three-dimensional structural diagram of the reaction chamber of a spiral gas-solid two-phase flow continuous synthesis apparatus.

[0024] Figure 3 This is a top view of the reaction chamber of a spiral gas-solid two-phase flow continuous synthesis apparatus.

[0025] Figure 4 The image shows the FTIR spectrum of the poly(p-phenylene diamine) prepared in Example 1.

[0026] Figure 5 The image shows the XRD pattern of poly(p-phenylene diamine) prepared in Example 1.

[0027] Figure 6 The image shows the UV-vis image of the poly(p-phenylene diamine) prepared in Example 1.

[0028] Figure 7 The TG curve of poly(p-phenylene diamine) prepared in Example 1 is shown.

[0029] Figure 8 The images show scanning electron microscope (SEM) images of poly(p-phenylenediamine) prepared in Example 1 and Comparative Example 3, where (a) is the SEM morphology of PpPD-1 at 1 μm, (b) is the SEM morphology of PpPD-1 at 100 nm, (c) is the SEM morphology of PpPD-2 at 1 μm, and (d) is the SEM morphology of PpPD-2 at 100 nm.

[0030] Figure 9 This is a particle size distribution diagram of the poly(p-phenylene diamine) prepared in Example 1.

[0031] Figure 10 The particle size distribution diagram is for the poly(p-phenylene diamine) prepared in Comparative Example 3.

[0032] Figure 11 This is a diagram showing the absorption pathway of nitrogen oxides by poly(p-phenylene diamine) prepared in Example 1.

[0033] Reference numerals in the attached diagram: 1-Material discharge pipeline; 2-Exhaust port; 3-Feed pipeline; 4-Carrier gas inlet pipeline; 5-Gas discharge pipeline; 6-Reaction chamber shell wall; 7-Machine shell; 8-Outer ring reaction chamber; 9-Inner ring reaction chamber; 10-Reaction chamber top cover; 11-Collection tank; 12-Feed inlet; 13-Gas distributor; 14-Inlet pipeline; 15-Reaction chamber; 16-Nozzle; 17-Connecting port. Detailed Implementation

[0034] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] The structure of the spiral gas-solid two-phase flow reactor provided in this embodiment is as follows: Figure 1 , Figure 2 and Figure 3 As shown, the system includes a reaction chamber top cover 10 and a housing 7. The reaction chamber top cover 10 and the housing 7 are closed by a detachable snap-fit ​​to form a sealed reaction chamber 15. A reaction chamber shell wall 6 is fixed inside the housing 7, dividing the reaction chamber 15 into an inner ring reaction chamber 9 and an outer ring reaction chamber 8 surrounding the inner ring reaction chamber 9. Four nozzles 16 are provided on the reaction chamber shell wall 6, which are arranged in the same direction deviating from the radial direction. The four nozzles 16 are all deviated from the radial direction at an angle of 30° and are arranged in a counterclockwise or clockwise manner to connect the inner ring reaction chamber 9 and the outer ring reaction chamber 8. The reaction chamber top cover 10 has three interfaces, which are respectively connected to the feed pipe 3, the carrier gas inlet pipe 4, and the gas outlet pipe 5. The three are connected to the inner cavity of the chamber only through the top cover interface, and the pipe bodies do not extend into the interior of the housing 7. One end of the feed pipe 3 is connected to the inner ring reaction chamber 9, and the other end is connected to the gas inlet pipe 14. The side wall of the gas inlet pipe 14 is provided with a feed port 12. With the help of the sample gas introduced from the gas inlet pipe 14, the raw material powder added from the feed port 12 is carried into the inner ring reaction chamber 9. The carrier gas inlet pipe 4 is connected to the outer ring reaction chamber 8 and is used to introduce high-pressure carrier gas into the outer ring reaction chamber 8. Then, it enters the inner ring reaction chamber 9 through the nozzle 16 on the reaction chamber shell wall 6, so that the high-pressure airflow forms a spiral airflow field in the inner ring reaction chamber 9, which drives the raw material powder added from the feed pipe 3 to perform high-speed spiral motion in it. A connecting port 17 is opened in the center of the inner ring reaction chamber 9. The connecting port 17 is arranged on the same axis as the gas discharge pipe 5, and there is a gap between the upper end of the connecting port 17 and the gas discharge pipe 5. The lower end of the connecting port 17 is connected to the material discharge pipe 1, and the other end of the material discharge pipe 1 is connected to the collection tank 11 for collecting reaction products. The gas that has completed energy exchange passes through the gap at the upper end of the connecting port 17 and is discharged from the reaction device through the gas discharge pipe 5 and the exhaust port 2 in sequence; the target product particles generated in the inner ring reaction chamber 9 enter the collection tank 11 through the connecting port 17 and the material discharge pipe 1 to realize the continuous collection of the product.

[0036] During operation, the premixed raw material powder enters through inlet 12, is carried by the sample gas from inlet pipe 14, and is sent into the inner ring reaction chamber 9 via inlet pipe 3. High-pressure carrier gas sequentially enters the outer ring reaction chamber 8 via gas distributor 13 and carrier gas inlet pipe 4, and is then sprayed into the inner ring reaction chamber 9 through four nozzles deviating from the radial direction, forming a high-speed spiral airflow field. This spiral airflow field drives the raw material powder to move in a high-speed spiral motion. The friction and collision between the solid particles of the raw material powder triggers an oxidative polymerization reaction. Simultaneously, utilizing the self-grading function of the spiral airflow field, the low-speed, low-pressure gas after energy exchange migrates towards the center and is discharged through gas outlet pipe 5 and exhaust port 2, requiring filtration through a dust collector bag before discharge. Under the centrifugal force generated by the spiral flow field, coarse raw material particles remain in the inner ring reaction chamber 9 to continue colliding and reacting, while the generated fine poly(p-phenylene diamine) particles migrate towards the center of the inner ring reaction chamber 9 and enter the collection tank 11 via connecting port 17 and material discharge pipe 1. During operation, the material is crushed and the reaction is promoted by the rotational motion trajectory. This can prevent tough and sticky materials from adhering to the inner wall of the reaction chamber and clogging the space. Furthermore, the product is continuously discharged through the product collection pipeline, realizing the continuous preparation of materials.

[0037] The continuous production process of poly(p-phenylene diamine) using spiral gas-solid two-phase flow (S-GSF) technology involves feeding premixed raw material powder at a feed rate of 1.5 g / min, with the feed gas blowing the reactants into reaction chamber 15. This creates a high-speed spiral flow field in the inner ring reaction chamber 9. This airflow drives the reactant particles into a high-speed spiral motion, causing intense collisions and friction between particles. This strong mechanical action significantly reduces the particle size of the material, increases the reactivity, and converts the enormous mechanical energy into the internal energy required for the chemical reaction, initiating the formation of polymer products. Under the centrifugal force generated by the spiral flow field, coarse raw material powder particles remain in the inner ring reaction chamber 9 and continue to collide and react. Meanwhile, the airflow resistance overcomes the centrifugal force acting on the fine particles of product, causing the product to gradually move radially towards the center of the reaction chamber, eventually falling into the collection tank 11 from the outlet below the center. After energy exchange, the low-speed, low-pressure gas leaves the reaction chamber through the outlet above the center, is filtered by a dust collector bag, and is then discharged into the atmosphere. Because S-GSF provides strong mechanical action and efficient material mixing, reactants can be completely converted into products before leaving the reaction chamber, thus enabling efficient and continuous chemical preparation. The final product is obtained in collection tank 11 without further purification.

[0038] The following is an example of the continuous preparation of poly(p-phenylene diamine) using a spiral gas-solid two-phase flow reactor.

[0039] Example 1 A method for preparing poly(p-phenylene diamine) as a stabilizer for nitrate ester compounds includes the following steps: The parameters of the pneumatic delivery unit were adjusted to ensure that the gas pressure entering the supersonic nozzle was 0.9 MPa (i.e., the gas pressure entering pipeline 4 through the carrier gas was 0.9 MPa). 1 mol of ammonium persulfate (APS) and 2 mol of p-phenylenediamine (pPD) were weighed, mixed thoroughly, and then added to the spiral gas-solid two-phase flow reactor at a feed rate of 1.5 g / min. The raw material solid particles rubbed and collided with each other under the action of the high-speed gas flow. Samples were taken every minute. When the powder in the collection tank changed from light green to black, the reaction was complete. The product was collected, yielding poly(p-phenylenediamine) (PpPD-1). The yield of poly(p-phenylenediamine) obtained in this example was 98.85%, with a corresponding space-time yield of 46.25 kg·m³. −3 ·h −1 The purity is 97%.

[0040] The structural formula of the poly(p-phenylene diamine) prepared in this embodiment is as follows: .

[0041] Example 2 A method for preparing poly(p-phenylenediamine) as a stabilizer for nitrate ester compounds, prepared according to the method shown in Example 1, except that the amounts of ammonium persulfate and p-phenylenediamine are both 1 mol.

[0042] The yield of poly(p-phenylene diamine) prepared using the method of this embodiment is 85.96%.

[0043] Example 3 A method for preparing poly(p-phenylenediamine) as a stabilizer for nitrate ester compounds, prepared according to the method shown in Example 1, except that the amounts of ammonium persulfate and p-phenylenediamine are 1 mol and 1.5 mol, respectively.

[0044] The yield of poly(p-phenylene diamine) prepared using the method of this embodiment is 93.54%.

[0045] Example 4 A method for preparing poly(p-phenylene diamine) as a stabilizer for nitrate ester compounds, prepared according to the method shown in Example 1, except that the parameters of the gas delivery unit are adjusted so that the gas pressure entering the supersonic nozzle is 0.5 MPa.

[0046] The yield of poly(p-phenylene diamine) obtained in this embodiment was 73.31%.

[0047] Example 5 A method for preparing poly(p-phenylene diamine) as a stabilizer for nitrate ester compounds, prepared according to the method shown in Example 1, except that the parameters of the gas delivery unit are adjusted so that the gas pressure entering the supersonic nozzle is 0.7 MPa.

[0048] The yield of poly(p-phenylene diamine) obtained in this embodiment was 86.57%.

[0049] Example 6 A method for preparing poly(p-phenylene diamine) as a stabilizer for nitrate ester compounds, prepared according to the method shown in Example 1, except that the parameters of the gas delivery unit are adjusted so that the gas pressure entering the supersonic nozzle is 1.1 MPa.

[0050] The yield of poly(p-phenylene diamine) obtained in this embodiment was 92.86%.

[0051] Comparative Example 1 Commonly available diphenylamine stabilizers.

[0052] Comparative Example 2 Commercially available N,N'-dimethyl-N,N'-diphenylurea stabilizers.

[0053] Comparative Example 3 The traditional chemical synthesis method for poly(p-phenylene diamine) (PpPD-2) is as follows: 0.05 mol of p-phenylenediamine was dissolved in 160 mL of 1 mol / L hydrochloric acid and magnetically stirred for 30 min in an ice-water bath at 0–5 °C to prepare a p-phenylenediamine hydrochloride solution, denoted as solution A. 0.05 mol of ammonium persulfate was dissolved in 40 mL of 1 mol / L hydrochloric acid and cooled in an ice-water bath to prepare an ammonium persulfate solution, denoted as solution B. Solution B was added dropwise to solution A over 2.5 hours. After the addition was complete, the reaction was continued for 24 hours under ice-water conditions. The mixture was then filtered, the precipitate was collected, and repeatedly washed with ethanol and water. Finally, it was washed with 1 mol / L hydrochloric acid. The filter cake was vacuum dried at 60 °C for 24 hours to obtain poly(p-phenylenediamine), named PpPD-2.

[0054] Performance testing FTIR, UV-Vis, TG, and XRD tests confirmed that the sample prepared in Example 1 was poly(p-phenylene diamine), and the results are shown in the figure. Figure 4 , Figure 5 , Figure 6 and Figure 7 . Figure 4 The images show the FTIR spectra of p-phenylenediamine (pPD) and poly(p-phenylenediamine) (PpPD) prepared in Example 1. Figure 5 The XRD pattern of poly(p-phenylene diamine) prepared in Example 1 is shown below. Figure 6 The image shows the UV-vis image of the poly(p-phenylene diamine) prepared in Example 1. Figure 7 The TG curve of poly(p-phenylene diamine) prepared in Example 1 is shown.

[0055] FTIR spectra such as Figure 4 As shown, in the FTIR spectrum of poly(p-phenylene diamine), the benzene ring appears at 1630 cm⁻¹.-1 The C=C tensile vibration peak of pPD at 1595 cm⁻¹ transforms into that of PpPD at 1595 cm⁻¹. -1 and 1509cm -1 The characteristic peak at 1397cm. -1 and 1119cm -1 The peak at 827 cm⁻¹ represents the CN stretching vibration on the benzene ring. -1 The peak at 3376 cm⁻¹ represents the out-of-plane bending vibration of the CH bond on the benzene ring. In the FTIR spectrum of pPD, this peak is observed at 3376 cm⁻¹. -1 and 3305cm -1 There are obvious NH bond symmetric and antisymmetric stretching peaks at the point, while the NH peak of PpPD (3133 cm⁻¹) is different. -1 The peak shifts to a lower frequency region and broadens, indicating that the secondary amine is produced by a polymerization reaction.

[0056] XRD pattern as follows Figure 5 As shown, strong characteristic diffraction peaks appeared at 2θ = 9°, 16.7°, 20.3°, 22.6°, 24°, and 28°, indicating high crystallinity of PpPD. The diffraction peaks at 16.7° and 24° correspond to the periodic parallel and perpendicular scattering of the polymer chains, respectively. These results demonstrate the successful synthesis of poly(p-phenylene diamine) using this method.

[0057] The UV-Vis absorption spectrum results of PpPD are as follows: Figure 6 As shown, the absorption peak at 323 nm belongs to the π-π* transition of the benzene ring in poly(p-phenylene diamine). Furthermore, the broad peak observed at 429 nm indicates a polarization transition involving both the π-π* transition of the benzene ring and the n-π* transition of the quinone ring.

[0058] Thermogravimetric analysis was performed to assess the thermal stability of poly(p-phenylene diamine). Figure 7 As shown, PpPD experienced a mass loss of 3.5% at 200℃, which did not reach the decomposition temperature of nitrocellulose, indicating its good stability. The mass loss during the transition from room temperature to 200℃ mainly involved the loss of moisture and unreacted raw materials. The very small mass loss at this stage demonstrates the high purity of the product.

[0059] The following tests examined the stability of the poly(p-phenylene diamine) stabilizer (PpPD-1) prepared in Example 1, the diphenylamine (DPA) stabilizer in Comparative Example 1, the N,N'-dimethyl-N,N'-diphenylurea (C2) stabilizer in Comparative Example 2, and the poly(p-phenylene diamine) stabilizer (PpPD-2) prepared in Comparative Example 3 against nitrocellulose containing nitrate esters. Samples of the NC / stabilizer were prepared by mechanical mixing, with the stabilizer amounting to 3 wt% of the total weight of the nitrocellulose. The tests were then conducted using methyl violet paper, vacuum stability testing (VST), and thermogravimetric analysis. A self-made methyl violet tester was used to perform stability tests on the samples according to the national military standard method GJB-770B-2005, at a temperature of 134.5℃ and a sample size of 300 mg. A self-made vacuum stability tester was used to perform stability tests on the samples according to the national military standard method GJB-772A-97. The sample temperature was 100℃, the test time was 48 hours, and the sample volume was 100 mg. Thermogravimetric analysis (TGA) was performed on the sample according to the national military standard method GJB-772A-97 to evaluate its thermal stability. The test atmosphere was N2, the flow rate was 30 mL / min, the test temperature was 135℃, the isothermal time was 360 min, and the sample volume was 3.2 mg.

[0060] The test results are shown in Table 1.

[0061] Table 1. Test results of the stability performance of nitrocellulose with different stabilizers Table 1 lists the stability evaluation indicators for different stabilizers, namely, methyl violet paper color change time, VST outgassing amount, and weight loss rate. It can be seen that the methyl violet paper color change time for PpPD-1 and PpPD-2 is 123 min and 115 min, respectively; the VST outgassing amounts are 1.84 mL / g and 1.91 mL / g, respectively; and the weight loss rates after 6 hours of constant temperature are 6.6% and 7.6%, respectively. The stability of poly(p-phenylene diamine) (PpPD-1) prepared by S-GSF and PpPD-2 synthesized by chemical methods is significantly better than that of traditional stabilizers (diphenylamine (DPA) and N,N'-dimethyl-N,N'-diphenylurea (C2)). Furthermore, the stability of poly(p-phenylene diamine) (PpPD-1) prepared by S-GSF is superior to that of PpPD-2 synthesized by chemical methods. This is because during the S-GSF preparation process, the gas, as a continuous phase, can effectively disperse the raw material solid particles, avoiding particle sedimentation and agglomeration, and achieving more uniform mixing. Compared with traditional chemical synthesis methods, this method effectively improves the contact area and uniformity of reactants, accelerates the reaction rate, and avoids the use of organic solvents and catalysts. This results in a more homogeneous and structurally consistent PpPD composition with higher purity. Therefore, the poly(p-phenylene diamine) (PpPD-1) prepared by S-GSF exhibits superior stability. A comprehensive comparison of the stability of DPA, C2, and P-PSF on nitrocellulose containing nitrate esters shows that P-PSF provides better stability. This indicates that P-PSF prepared via spiral gas-solid two-phase flow can be used as a stabilizer, and that P-PSF prepared via S-GSF exhibits better stability against nitrate ester compounds.

[0062] Scanning electron microscope images of poly(p-phenylene diamine) prepared in Example 1 and Comparative Example 3 are shown below. Figure 8 As shown. Figure 8 In the figure, (a) is the SEM morphology of PpPD-1 at 1 μm, (b) is the SEM morphology of PpPD-1 at 100 nm, (c) is the SEM morphology of PpPD-2 at 1 μm, and (d) is the SEM morphology of PpPD-2 at 100 nm. Figure 9 and Figure 10 The figures show the particle size distributions of PpPD-1 and PpPD-2, respectively. As can be seen, the two PpPDs exhibit significant differences in microstructure. PpPD-1 (Example 1), prepared by the S-GSF method, displays a uniform nanoparticle structure with a narrow particle size distribution, ranging from 0.17 μm to 0.29 μm. In contrast, PpPD-2 obtained by the conventional chemical oxidation method (Comparative Example 3) exhibits a large-scale plate-like structure with particle sizes ranging from 0.73 μm to 1.09 μm. Notably, smaller and more uniform nanoparticles provide a larger contact area when preparing composite materials, thereby enhancing compatibility and stability.

[0063] The electrostatic potential of PpPD was calculated using first-principles calculations and visualized using Multiwfn and VMD, demonstrating the PpPD absorption pathway for nitrogen oxides. (See [link to relevant documentation]). Figure 11 The figure illustrates a unit of poly(p-phenylene diamine) as an example. The poly(p-phenylene diamine) provided by this invention is non-toxic and possesses a diphenylamine-like structure, significantly enhancing its absorption capacity for nitrogen oxides and improving its stability against nitrate esters. The specific mechanism of action is as follows: nitrate esters decompose to produce nitrogen oxides and acidic substances; nitrogen oxides (such as NO2) are converted to NO2 under acidic conditions. + According to the theory of conjugate electrophilic aromatic nitration, the substance that actually attacks the benzene ring is the positively charged NO2. + It extracts electrons from the benzene ring to form a positively charged intermediate, which then attaches a nitro group and loses a proton to yield nitrobenzene; on the other hand, the NO2 molecule is affected by H... + Activate, H + It also collides with the benzene ring to form a π-complex. The π-complex promotes the binding of the activated NO2 molecule to the benzene ring through spatial positioning and electronic regulation, ultimately transferring nitrobenzene (ArNO2). The above process does not produce nitrosamines.

[0064] The nitrogen oxides and acidic gases produced by the thermal decomposition of nitrate esters accelerate the decomposition reaction. Stabilizers are typically added to inhibit and mitigate this highly dangerous autocatalytic decomposition. However, common basic amine stabilizers are toxic, posing environmental pollution and health risks. This invention synthesizes poly(p-phenylene diamine) with a similar structure to DPA via a spiral gas-solid two-phase flow mechanochemical process. This avoids the use of toxic solvents in the preparation process. With its low cost, non-toxicity, ease of synthesis, and efficient removal of nitrogen oxides, it shows promise for use as a stabilizer for nitrate esters.

[0065] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the inventive concept of the present invention, can make other changes and modifications to these embodiments, all of which fall within the scope of the present invention.

[0066] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention also intends to include these modifications and variations.

Claims

1. The application of poly(p-phenylene diamine) as a stabilizer for nitrate ester compounds, characterized in that, Based on the total weight of nitrate ester compounds, the amount of poly(p-phenylene diamine) added is 2.9% to 3.1%.

2. The application of poly(p-phenylenediamine) as a stabilizer for nitrate ester compounds according to claim 1, characterized in that, The preparation method of poly(p-phenylene diamine) is as follows: Using p-phenylenediamine as a monomer and ammonium persulfate as an oxidant, a spiral gas-solid two-phase flow technology was adopted. Under the action of airflow, the raw material solid particles rub and collide with each other to initiate an oxidative polymerization reaction, thus producing poly(p-phenylenediamine).

3. The application of poly(p-phenylenediamine) as a stabilizer for nitrate ester compounds according to claim 2, characterized in that, The molar ratio of ammonium persulfate to p-phenylenediamine is 1:1 to 2.

4. The application of poly(p-phenylenediamine) as a stabilizer for nitrate ester compounds according to claim 2, characterized in that, The intake pressure of the airflow is 0.5MPa to 1.1MPa.

5. The application of poly(p-phenylenediamine) as a stabilizer for nitrate ester compounds according to claim 2, characterized in that, The particle size of poly(p-phenylene diamine) is 0.17 μm to 0.29 μm.

6. The application of poly(p-phenylenediamine) as a stabilizer for nitrate ester compounds according to claim 1, characterized in that, The preparation of poly(p-phenylene diamine) was carried out in a spiral gas-solid two-phase flow reactor.

7. The application of poly(p-phenylene diamine) as a stabilizer for nitrate ester compounds according to claim 6, characterized in that, The spiral gas-solid two-phase flow reactor includes a reaction chamber top cover (10) and a housing (7). The reaction chamber top cover (10) and the housing (7) are closed to form a sealed reaction chamber (15). The housing (7) has a ring of reaction chamber shell wall (6) fixed inside, which divides the reaction chamber (15) into an outer ring reaction chamber (8) and an inner ring reaction chamber (9). The top cover (10) of the reaction chamber is fixed with a feed pipe (3), a carrier gas inlet pipe (4) and a gas outlet pipe (5); the feed pipe (3) is connected to the inner ring reaction chamber (9) and carries the raw material powder into the inner ring reaction chamber (9) through the injection gas; the carrier gas inlet pipe (4) is connected to the outer ring reaction chamber (8) and is used to introduce carrier gas; Multiple nozzles (16) deviating from the radial direction are provided on the shell wall (6) of the reaction chamber. The carrier gas in the outer ring reaction chamber (8) enters the inner ring reaction chamber (9) along the multiple nozzles (16) to form a spiral airflow, which drives the raw material powder to rub and collide with each other, and initiates an oxidative polymerization reaction. The inner ring reaction chamber (9) has a connecting port (17) at its center. The connecting port (17) is set on the same axis as the gas discharge pipe (5), and there is a gap between the connecting port (17) and the gas discharge pipe (5) so that the gas after the oxidation polymerization reaction is completed can be discharged through the gas discharge pipe (5), and the product particles can be discharged through the connecting port (17).

8. The application of poly(p-phenylene diamine) as a stabilizer for nitrate ester compounds according to claim 7, characterized in that, Each nozzle (16) deviates from the radial direction by an angle of 30° to 45°.

9. The application of poly(p-phenylenediamine) as a stabilizer for nitrate ester compounds according to claim 1, characterized in that, The nitrate ester compound is nitrocellulose or nitroglycerin.

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