A novel dynamic simulation method for investigating the hygroscopicity of Ammonium perchlorate

Abstract

Ammonium perchlorate (AP) is a widely used oxidizer, extensively employed in solid propellants with excellent combustion properties. Ultrafine AP has better combustion properties, but its strong hygroscopicity and high sensitivity hinder its application. To safely and efficiently explore the hygroscopicity of ultrafine AP, this paper proposes a novel molecular dynamics (MD) simulation approach. By analyzing the movement of water molecules, fluctuations in average hydrogen bond strength, and the influence of non-covalent intermolecular forces throughout the moisture absorption process, this study presents a comprehensive overview of the hygroscopic properties of ultrafine AP across relative humidity (RH) levels spanning from 10 % to 100 %, and temperatures ranging between 273 K and 373 K. It was found that temperature has a more significant impact on the hygroscopicity of AP compared to RH. During the hygroscopic process of AP, Van der Waals interactions hindered the water absorption of AP, while electrostatic forces promoted its hygroscopic properties. The hygroscopicity of AP reached a maximum when the temperature exceeded 333 K, and plateaued as the increase of RH. The proposed moisture simulation method facilitates the secure and effective forecasting of moisture absorption in AP-based materials across various temperature and RH environments, thereby greatly expediting research on enhancing the moisture resistance of ultrafine AP.