Study On The Crystallization Thermodynamics And Crystal Morphology Control Of HMX

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocin is one of the best explosives in the world today.It is also the most comprehensive elementary explosive and high-energy explosive used in military and industrial applications,codenamed HMX.There are many researches on HMX,but there is no systematic and comprehensive research on its crystallization foundation.In response to this problem,this work carried out a series of basic research around the crystallization of HMX,which laid the foundation for its subsequent research and has important reference value and research significance.The main content of this paper is as follow:The research on crystallization thermodynamics of HMX.The solubility of HMX in 12 pure solvents was measured in the temperature range of 298.15 K~358.15 K by the static equilibrium method through high-performance liquid chromatography(HPLC).The experimental solubility data were correlated with the modified Apelblat model,the Yaws model and the Ideal solution model.The thermodynamic parameters such as the dissolution enthalpy and the dissolution entropy of HMX in various solvents were obtained by correlating the Van't Hoff equation.The results show that the solubility of HMX increases with increasing temperature in all test solvents.The dissolution process is endothermic,entropy-driven,and non-spontaneous.The research on crystal morphology of HMX.The crystal morphologies of HMX in vacuum and eight pure organic solvents were predicted based on the modified attachment energy model(AE)by using molecular dynamics method(MD).The aspect ratios of the predicted results were compared,and the spheroidization degree of the theoretical results of HMX was quantitatively characterized.The natural cooling method was used to recrystallize HMX to verify the accuracy of the AE model to the crystal morphology of HMX.The results show that HMX has five important crystal faces:(0 1 1),(1 1-1),(0 2 0),(1 0 0)and(1 0-2).The order of the aspect ratio of the crystal morphology is:cyclopentanone > cyclohexanone > N,N?dimethylacetamide(DMAC)> pyridine > acetone > triethyl phosphate > propylene carbonate > Dimethyl sulfoxide(DMSO).The AE model is suitable for predicting the crystal morphology of HMX.The research on crystal preparation and performance characterization of HMX.Recrystallization experiment of HMX in a series of solvents such as DMSO by cooling method,dissolution method and evaporation method respectively.HMX crystal samples with different morphologies were obtained and a series of commonly used performance characterizations were performed,such as crystal form,purity and thermal performance.The results show that the cooling method can obtain fusiform-like,rod-like,needle-like and X-like crystals,and the crystal forms are all ?-HMX.The solvent-antisolvent method obtains fusiform-like,bulk and rod-liked crystals.And the crystal transition temperature of ?-HMX??-HMX is all postponed,and the postponed range is 2.3~13.3 ?.Four types of crystal samples were obtained by evaporation: fusiform-like,hexagonal-liked,rod-liked and X-liked crystals.