微观尺度下黏结剂预聚物体系中硝酸酯的分解老化机制  

Decomposition and Aging Mechanism of Nitrate Esters in Binder Prepolymer System at Microscopic Scale

作　　者：付健博 任慧[1] 刘晓晗 孙建军 吴国卿 FU Jianbo;REN Hui;LIU Xiaohan;SUN Jianjun;WU Guoqing(State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology,Beijing 100081,China;Inner Mongolia Synthetic Chemical Research Institute,Hohhot 010010,China)

机构地区：[1]北京理工大学爆炸科学与安全防护全国重点实验室,北京100081 [2]内蒙合成化工研究所,呼和浩特010010

出　　处：《装备环境工程》2024年第10期16-25,共10页Equipment Environmental Engineering

基　　金：国家重点研发计划(2021YFC2902904);国家自然科学基金(21975024)。

摘　　要：目的研究硝酸酯黏合剂预聚物中硝酸酯的分解、老化及相应的微观变化机理。方法利用反应分子动力学模拟NG/BTTN/PEG复合体系的热分解过程,基于此过程设计不同老化程度的硝酸酯分子。通过第一性原理计算结合经典分子动力学模拟,对硝酸酯分解老化导致的静电势分布、分子极性、分子间弱相互作用等一系列微观变化进行理论计算。结果硝酸酯黏结剂预聚物中NG和BTTN的初始分解均以脱硝基反应为主导,随后C—C键发生裂解。这种裂解是由于前线轨道的变化引起解离能下降导致的。随着硝酸酯分子分解老化程度的加剧,分子表面的静电势分布逐渐趋向于电中性,老化导致NG和BTTN的分子极性先增大、后减小。老化过程分子间相互作用的退化,主要由PEG分子上的O和硝酸酯分子上的H原子对间氢键作用的大幅减弱导致。结论硝酸酯的分解老化减弱了与黏结剂分子间的静电吸引,改变了分子极性,弱化了分子间的氢键及范德华相互作用。老化过程的微观机制研究对于预测推进剂力学性能退化、组分迁移等宏观性能变化规律具有重要意义。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.

关 键 词：老化机理 硝酸酯 NEPE推进剂 热分解 分子动力学 密度泛函理论 

分 类 号：V512[航空宇航科学与技术—航空宇航推进理论与工程]