Study On The Crystallization Process Of FOX-7

FOX-7?1,1-diamino-2,2-dinitroethylene?is a kind of high energy insensitive material with excellent comprehensive properties.The FOX-7 crystal obtained by crystallization process has some problems,such as irregular shape,poor density,etc.,which cannot show its optimal performance in practical application.Therefore,it is of great significance to study the crystallization process of FOX-7.In this paper,the crystallization process of FOX-7 in DMF system was studied.The solubility and supersolubility of FOX-7 was determined by laser dynamic method in N-dimethylformamide?DMF?,water?H₂O?,ethanol,acetone and DMF/H₂O,DMF/ethanol,DMF/acetone mixed solvents.And the data were correlated by the modified Apleblat model,?CNIBS?/Redlich-Kister model.The solubility thermodynamics parameters of FOX-7 were calculated by van't Hoff equation,and the solid-liquid surface tension and crystal surface entropy factor of FOX-7 were calculated by Mersmann equation and BARATA equation.The results show that DMF is a good solvent for FOX-7,H₂O,ethanol and acetone are bad solvents,and the dissolution process of FOX-7 is endothermic and non-spontaneous.After comparing the crystallization effect of FOX-7 in DMF,DMF/H₂O,DMF/ethanol and DMF/acetone,the optimal crystallization solvent system was selected.The kinetic process data of FOX-7 in DMF/H₂O binary system were measured by intermittent dynamic method.The nucleation rate equation and crystal growth rate equation of FOX-7 were established.The effects of supersaturation,temperature,stirring intensity and suspension density on FOX-7 were analyzed.The results show that the crystal growth of FOX-7 in the above system is particle size independent,and the effect of supersaturation on nucleation is greater than that on crystal growth.The crystallization process of FOX-7 in DMF/H₂O binary system was studied by single factor optimization and orthogonal test.The effects of different temperature,stirring rate,cooling rate,additive type and dosage on the crystal morphology were compared,and the better crystallization process of FOX-7 was obtained.The results show that when V_DMF:V_H2O=7:3,PEG-400 is used as additive and the dosage is 0.5%,the initial temperature is 65?,the stirring rate is 500r/min,and the cooling rate is 0.5?/min,the crystallized product has good compactness and spherical shape.This paper have certain significance for improving FOX-7 crystallization technology,perfecting crystal quality,making performance and application better.