NC/NG共混体系的塑化行为

Study on Plasticizing Process of NC/NG Blends

关键词:  物理化学  塑化  分子动力学模拟  复合改性双基推进剂 

Key words:  Physical chemistry  Plasticizing process  Molecular dynamics simulation  Composite modified double-base propellant

摘要:

为了解硝化纤维素(NC)/硝化甘油(NG)塑化行为的实质,用动态流变学方法和红外光谱法对其塑化行为的宏观性质表现进行测量,并在此基础上通过分子动力学模拟揭示NC在塑化过程中的微观结构变化。结果表明,NC/NG共混体系的储能模量(G′)和损耗模量(G″)随塑化时间逐渐增大,且G′逐渐接近并超过G″,二者最终趋于稳定,此过程中体系的某些与氢键有关的红外特征频率向低波数移动。分子动力学模拟表明,在NC/NG共混体系塑化过程中,NG分子的空间位阻作用使NC分子链自由体积增加；另一方面NG分子与NC分子形成的氢键替代了NC分子内氢键,使NC分子链内部作用力减弱,回转半径增大。 

Abstract:

In order to explore the essence of plasticizing of nitrocellulose (NC)/nitroglycerine (NG) blends, the plasticizing process of NC/NG blends was investigated by means of the dynamic rheology method and infrared spectroscopy, and the interaction between NC and NG molecular was calculated by using Molecular Dynamics simulation(MD). The results show that the storage modulus( G′) and loss modulus (G″) increase significantly, G′ and G″ increase to the maximum and level off, and then G′ is higher than G″. In the addition, the infrared characteristic frequency decreases due to change of H-bond of NC/ NG blends in plasticizing process. Besides, according to the calculation results of Molecular Dynamics simulation, it is revealed that the free volume of NC molecule is increased by the steric hindrance effect of NG molecule, and the H-bond can be formed between NG and NC molecules instead of H-bond in the individual NC molecule, thus increasing the radius of gyration of NC. 