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| Decomposition and Aging Mechanism of Nitrate Esters in Binder Prepolymer System at Microscopic Scale |
| Received:June 03, 2024 Revised:July 08, 2024 |
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| DOI：10.7643/issn.1672-9242.2024.10.002 |
| KeyWord:aging mechanism nitrate ester NEPE propellant thermal decomposition molecular dynamics DFT |
| Author | Institution |
| FU Jianbo |
State Key Laboratory of Explosion Science and Safety Protection, Beijing Institute of Technology, Beijing , China |
| REN Hui |
State Key Laboratory of Explosion Science and Safety Protection, Beijing Institute of Technology, Beijing , China |
| LIU Xiaohan |
Inner Mongolia Synthetic Chemical Research Institute, Hohhot , China |
| SUN Jianjun |
Inner Mongolia Synthetic Chemical Research Institute, Hohhot , China |
| WU Guoqing |
Inner Mongolia Synthetic Chemical Research Institute, Hohhot , China |
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| Abstract: |
| The work aims to study the decomposition, aging, and corresponding microscopic mechanisms of nitrate esters in nitrate ester-based adhesive prepolymers. The reactive molecular dynamics was utilized to simulate the thermal decomposition process of the NG/BTTN/PEG composite system. Based on this process, nitrate ester molecules with varying degrees of aging were designed. First-principles calculations combined with classical molecular dynamics were employed to theoretically calculate the microscopic changes caused by the decomposition and aging of nitrate esters, such as electrostatic potential distribution, molecular polarity, and intermolecular weak interactions. In the nitrate ester binder prepolymer, the initial decomposition of both NG and BTTN was predominantly driven by denitration reactions, followed by cleavage of C-C bonds. This cleavage was attributed to a decrease in dissociation energy caused by changes in frontier orbitals. As the degree of nitrate ester decomposition and aging intensified, the electrostatic potential distribution on the molecular surface gradually approached neutrality. The aging process initially increased and then decreased the molecular polarity of NG and BTTN. The degradation of intermolecular interactions during aging was mainly due to a significant reduction in hydrogen bonding between oxygen atoms on PEG molecules and hydrogen atoms on nitrate ester molecules. The decomposition and aging of nitrate esters weaken the electrostatic attraction between binder molecules, alter molecular polarity, and reduce hydrogen bonding and van der Waals interactions. The study of the microscopic mechanism of aging process is of great significance for predicting the macroscopic properties of propellants such as mechanical degradation and component migration. |
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