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Guo G, Chen F, Li T, Dong L, Wang J, Cao D. Multi-aspect and comprehensive atomic insight: the whole process of thermolysis of HMX/Poly-NIMMO-based plastic bonded explosive. J Mol Model 2023; 29:392. [PMID: 38038765 DOI: 10.1007/s00894-023-05795-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Accepted: 11/23/2023] [Indexed: 12/02/2023]
Abstract
Based on the reactive molecular dynamics, the whole process of thermolysis of HMX/Poly-NIMMO-based PBX was studied in detail at the micro scale, which provided a novel atomic insight into the thermolysis mechanism of HMX/Poly-NIMMO. Further, it was compared with the HMX single substance system to explore the influence of binder on thermolysis of HMX. According to the findings, the activation energy required by pyrolysis of HMX in the mixed system is much less than that required by the pure HMX system at both phases. From the point of view of reaction energy, poly-NIMMO promoted the thermolysis of HMX. Especially, the mechanism analysis confirmed this point. The nitro and hydroxyl groups detached from Poly-NIMMO will react with HMX, and the generated HNO2 will further accelerate the decomposition process of nitrogen heterocycles. In addition, the number of the final products H2O and H2 in the two-component system increased greatly, but the number of CO2 and N2 molecules had not changed much, and C clusters were formed in the system. The evolution trend of bond number further verified the above analysis. While the maximum cluster number does drop with increasing temperature at first, after a particular temperature threshold is reached, it remains unchanged. In a nutshell, poly-NIMMO will hasten HMX's thermolysis and reduce the system's stability when subjected to heat.
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Affiliation(s)
- Guoqi Guo
- School of Chemistry and Chemical Engineering, North University of China, Taiyuan, 030051, Shanxi, China
| | - Fang Chen
- School of Chemistry and Chemical Engineering, North University of China, Taiyuan, 030051, Shanxi, China.
| | - Tianhao Li
- School of Chemistry and Chemical Engineering, North University of China, Taiyuan, 030051, Shanxi, China
| | - Ling Dong
- School of Chemistry and Chemical Engineering, North University of China, Taiyuan, 030051, Shanxi, China
| | - Jianlong Wang
- School of Chemistry and Chemical Engineering, North University of China, Taiyuan, 030051, Shanxi, China
| | - Duanlin Cao
- School of Chemistry and Chemical Engineering, North University of China, Taiyuan, 030051, Shanxi, China
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Mao JS, Wang BG, Zhu R, Chen YF, Fu JB. Investigation of the decomposition mechanism of MTNP melt-cast explosive at different temperatures and pressures through ReaxFF/lg molecular dynamics simulations. J Mol Model 2023; 29:354. [PMID: 37910219 DOI: 10.1007/s00894-023-05760-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 10/22/2023] [Indexed: 11/03/2023]
Abstract
CONTEXT Thermal decomposition of 1-methyl-3,4,5-trinitropyrazole (MTNP), a melt-cast explosive, was investigated at different temperatures (2500, 2750, 3000, 3250, and 3500 K) and pressures (3000 K/0.5 GPa, 3000 K/1 GPa) using the ReaxFF/lg force field. The study aimed to analyze the changes in reactant quantities, initial reaction pathways, and final product yields. The results demonstrated that complete decomposition of MTNP molecules occurred within a timeframe of 200 ps, with shorter decomposition times observed as the temperature increased. The high-temperature thermal decomposition of MTNP was found to follow two primary reaction pathways. Reaction 1 involved denitration, while reaction 2 proceeded with nitro group isomerization. DFT calculations indicated that nitro group isomerization was the most favorable reaction. During the initial stages, higher quantities of NO2, NO, and N2 were observed compared to other species. This can be attributed to the relatively higher nitrogen and oxygen content in the MTNP structure. Among the five reaction temperatures, it was observed that the quantities of small molecules followed the order of NO2 > NO > N2 > CO. Moreover, with increasing temperature, the quantities of all four small molecules increased, indicating that higher temperatures promoted the progression of the reactions. However, as the pressure increased, there was a trend of initially increasing and then decreasing to zero for the quantities of NO2 and NO. This suggests that high temperature accelerated the high-temperature thermal decomposition of NO2 and NO, leading to a significant increase in the content of N2. METHODS A 3 × 5 × 5 supercell model of MTNP was constructed in Materials Studio, consisting of 75 unit cells and 300 MTNP molecules. The model was then subjected to a 20 ps geometric optimization using the Polak-Ribiere version of the conjugate gradient (CG) algorithm in the large-scale atomic/molecular massively parallel simulator (LAMMPS) under the isothermal-isobaric (NPT) ensemble at 1 atm pressure and 300 K temperature. Following the optimization, molecular dynamics simulations were performed on the model at five temperatures (2500, 2750, 3000, 3200, and 3500 K) under 1 atm using the NPT ensemble for a total duration of 1 ns. During the simulations, atomic trajectories, as well as information on atomic and molecular species, were output every 500 steps. Subsequently, a custom script was utilized to analyze the thermal decomposition pathways and products. A time step of 0.1 fs was employed for the calculations, and periodic boundary conditions were applied to eliminate boundary effects.
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Affiliation(s)
- Jian-Sen Mao
- School of Environmental and Safety Engineering, North University of China, Taiyuan, 030051, China
| | - Bao-Guo Wang
- School of Environmental and Safety Engineering, North University of China, Taiyuan, 030051, China.
| | - Rui Zhu
- School of Environmental and Safety Engineering, North University of China, Taiyuan, 030051, China
| | - Ya-Fang Chen
- School of Environmental and Safety Engineering, North University of China, Taiyuan, 030051, China
| | - Jian-Bo Fu
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing, 100081, China
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Yuan X, Huang Y, Zhang S, Gou R, Zhu S, Guo Q. Multi-aspect simulation insight on thermolysis mechanism and interaction of NTO/HMX-based plastic-bonded explosives: a new conception of the mixed explosive model. Phys Chem Chem Phys 2023; 25:20951-20968. [PMID: 37496442 DOI: 10.1039/d3cp00494e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Reactive molecular dynamics (RMDs) calculations were used to determine, for the first time, the process of thermolysis of the mixed explosives, including 3-nitro-1,2,4-triazol-5-one (NTO) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazoline (HMX). Significantly, this is the first time that a layered model for mixed explosives, which is an extreme innovation of mixed explosive models was adopted. It is shown that a large amount of NO2 in the HMX and OH groups generated by the decomposition of HNO2 has a favorable effect on the thermolysis of NTO, as further validated by a reduction in the activation energy of NTO/HMX. The amount of H2O and N2 in the resulting products increased significantly, but the amount of NH3 changed slightly. The analysis results correspond to the change in chemical bonds. Whenever there is an increase in temperature, the time for the maximum number of clusters to appear is shortened accordingly. In addition, the acidity of NTO has been considered. An independent gradient model based on Hirshfeld partition (IGMH) and atoms in molecule (AIM) analysis of NTO/HMX was implemented. The relatively strong hydrogen bonds indicate that HMX can inhibit the acidity of NTO and is beneficial for the wide application of NTO/HMX-based plastic-bonded explosives (PBXs).
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Affiliation(s)
- Xiaofeng Yuan
- School of Environment and Safety Engineering, North University of China, Taiyuan 030051, Shanxi, China.
| | - Ying Huang
- School of Environment and Safety Engineering, North University of China, Taiyuan 030051, Shanxi, China.
| | - Shuhai Zhang
- School of Environment and Safety Engineering, North University of China, Taiyuan 030051, Shanxi, China.
| | - Ruijun Gou
- School of Environment and Safety Engineering, North University of China, Taiyuan 030051, Shanxi, China.
| | - Shuangfei Zhu
- School of Environment and Safety Engineering, North University of China, Taiyuan 030051, Shanxi, China.
| | - Qianjin Guo
- School of Environment and Safety Engineering, North University of China, Taiyuan 030051, Shanxi, China.
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Xiao Q, Sui H, Yin Y, Liao L, Wang H, Fu X, Wang J, Ai J, Ju X. Research on the gamma irradiation decomposition products of 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105). Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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ReaxFF/lg molecular dynamics study on thermolysis mechanism of NTO/HTPB plastic bonded explosive. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2022.113834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Bai H, Gou R, Chen M, Zhang S, Chen Y, Hu W. ReaxFF/lg molecular dynamics study on Thermal decomposition Mechanism of 1-methyl-2,4,5-trinitroimidazole. COMPUT THEOR CHEM 2022. [DOI: 10.1016/j.comptc.2022.113594] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Zhu S, Yang W, Gan Q, Cheng N, Feng C. Early thermal decay of energetic hydrogen- and nitro-free furoxan compounds: the case of DNTF and BTF. Phys Chem Chem Phys 2021; 24:1520-1531. [PMID: 34935783 DOI: 10.1039/d1cp02881b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Exploration of the initial reactions of H-free and nitro-free energetic materials could enrich our understanding of the thermal decomposition mechanism of various energetic materials (EMs). In this work, two furoxan compounds, 3,4-dinitrofurazanfuroxan (DNTF) and benzotrifuroxan (BTF), were investigated to shed light on the decay mechanism of furoxan compounds based on the combination of self-consistent charge density functional tight binding and molecular dynamics simulations. The results show that DNTF and BTF decay via a unimolecular mechanism, and the transformation of the furoxan ring into a nitro group is suggested as a novel initial channel. Five initial steps of DNTF thermal decomposition are observed, including NO2 loss and the N(O)-O bond cleavage of the central and peripheral rings. The bond cleavage of peripheral rings dominates the decay at low temperatures, while the central ring opening and C-NO2 dissociation govern the high temperature decay. Besides, NO2, CO and NO fragments are mainly yielded at high temperatures, while CO3N2 is dominant at low temperatures. The three-stage characteristic of the exothermic BTF decay is described under programmed heating conditions for the first time. Four initial steps of BTF thermal decomposition were identified, including furoxan ring opening reactions and the breakage of the 6-membered ring C-C bond. The cleavage of the N(O)-O bond is dominant in the initial step of BTF decomposition under different heating conditions, and the frequency increases with increasing temperature. In addition, the amounts of CON, ON and CO are higher at high temperatures, while C2O2N2 shows an opposite trend. The findings of this work provide deep insights into the complicated sensitivity mechanism of EMs.
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Affiliation(s)
- Shuangfei Zhu
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
| | - Wei Yang
- School of Materials Science & Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Qiang Gan
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
| | - Nianshou Cheng
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
| | - Changgen Feng
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
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Zhu S, Yang W, Gan Q, Feng C. Comparative Quantum Chemistry Study on the Unimolecular Decomposition Channels of Pyrazole and Imidazole Energetic Materials. J Phys Chem A 2021; 125:10340-10350. [PMID: 34843232 DOI: 10.1021/acs.jpca.1c08274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The difference in the initial decomposition step of pyrazoles and imidazoles was explored using the M062X method for optimization and G4-MP2 and approximated CCSD(T) methods for energies. Laplacian bond order analysis was used to study the effect of the nitro group on the bond strength and predict the bond dissociation energy (BDE) of the ring. Thermochemistry results show that the most possible decay channel of 1H-pyrazole and 3-nitropyrazole is the N2 elimination, while the preferred initial step of 1H-imidazole is the CHN elimination. However, the nitro-nitrite isomerization dominates the decomposition of other nitro derivatives of 1H-pyrazole and 1H-imidazole. As for the formation of HO and HONO, the high energy barrier makes it difficult to take place. Based on the analysis of the lowest energy barrier and the BDE of NO2 loss, it can be concluded that imidazoles are more stable than pyrazoles. This work contributes to revealing the difference in the initial step of energetic isomers and the understanding of the decomposition mechanism of energetic azoles.
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Affiliation(s)
- Shuangfei Zhu
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China
| | - Wei Yang
- School of Materials Science & Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Qiang Gan
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China
| | - Changgen Feng
- State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China
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Jiang J, Liu J, Chen Y, Wu Q, Ju Z, Zhang S. Detonation response mechanism of shocked LLM-105 using ReaxFF-lg and MSST. MOLECULAR SIMULATION 2021. [DOI: 10.1080/08927022.2021.1902517] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Jun Jiang
- College of Environment and Safety Engineering, North University of China, Taiyuan, People’s Republic of China
- National Key Laboratory of Applied Physics and Chemistry, Xi’an, People’s Republic of China
| | - Jiayun Liu
- Beijing Institute of Space Long March Vehicle, Beijing, People’s Republic of China
| | - Yahong Chen
- College of Environment and Safety Engineering, North University of China, Taiyuan, People’s Republic of China
| | - Qiuhong Wu
- College of Environment and Safety Engineering, North University of China, Taiyuan, People’s Republic of China
| | - Zeyu Ju
- College of Environment and Safety Engineering, North University of China, Taiyuan, People’s Republic of China
| | - Shuhai Zhang
- College of Environment and Safety Engineering, North University of China, Taiyuan, People’s Republic of China
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