Precipitation crystallization of HNIW in ethyl acetate/n-heptane system
2,4,6,8,10,12-Hexanitrohexaazaisowurtzitane (HNIW, or CL-20) has four crystalline phases(a, β, γ and ε) at ambient conditions.Crystallization process of HNIW was investigated by adopting precipitation method by adding n-heptane (antisolvent) to the HNIW ethyl acetate (solvent) solution under various conditions, which included different solvent-antisolvent ratio, concentration of HNIW ethyl acetate solution, crystallization batch dosage and antisolvent addition rate.Crystal polymorph and morphology of HNIW were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM).Results revealed that pure β-HNIW, pure ε-HNIW and mixtures of β-HNIW and ε-HNIW can be attained and the polymorphic transformation from β-HNIW to ε-HNIW occurs with the 110ml/s addition rate of heptane.Whereas, when the n-heptane addition rate is 20ml/s, only ε-HNIW nucleus formed and growed without phase transition in the whole crystallization processes.Experiments and theory simulation revealed that crystallization mechanisms of HNIW are mainly dynamic control and thermodynamic control when the addition rates ofn-heptane are 110ml/s and 20ml/s, respectively.
HNIW precipitation crystallization polymorphic transformation crystallization mechanism
ZHOU Xiaoqing ZHANG Qi WANG Shucun XU Rong YANG Zongwei LI Hongzhen
Institute of Chemical Materials,China Academy of Engineering Physics,Mianyang,Sichuan 621900,China
国际会议
成都
英文
547-553
2013-09-24（万方平台首次上网日期，不代表论文的发表时间）