Study On The Regulation Of TATB Crystal Morphology By New Composite Solvents

The crystal morphology such as appearance,size,agglomeration state of explosives will not only affect the macroscopic mechanical properties of explosives,but also affect their sensitivity and explosion properties.To effectively regulate the crystal morphology of explosive is expected to improve its comprehensive properties such as energy,safety and mechanical properties,which has important application significance,and is the focus of insensitive high explosives in current research.As the only single compound explosive that meets the standard of low-sensitivity high-energy explosive at present,1,3,5-triamino-2,4,6-trinitrobenzene(TATB)has important application value in both military and civilian fields because of its high energy density and excellent safety performance.However,the strong intra-molecular and inter-molecular hydrogen bonds in TATB molecule make its crystal take on a flake shape,which is not easy to grow and break easily.Moreover,the solubility of TATB in most solvents is so poor that it is difficult to regulate the crystal morphology of TATB,which significantly limits the application prospect of TATB.In this thesis,in order to solve the problem that it is difficult to regulate the morphology of TATB crystals caused by the poor solubility of TATB crystals caused by conventional solvents,a series of new composite solvents were designed and prepared.First of all,the study of the solubility of TATB in composite solvents was carried out,and on the basis of the solubility study,the regulation of TATB crystal morphology was carried out by using different recrystallization methods based on the characteristics of composite solvents.The large TATB crystals which are difficult to be obtained by conventional solvents were prepared at room temperature.Then,based on the efficient dissolution of TATB by the new composite solvent,the nano-composite grains of high explosive and nano-TATB were prepared by solvent-induced self-assembly,which can effectively reduce the sensitivity of high explosive while maintaining high energy.The main works of this thesis are as follows:1.Based on the previous research on the new deep eutectic solvent(CS-1)with high solubility of TATB,aiming at the difficulty of morphology regulation and separation of TATB crystal caused by the high viscosity of CS-1,this thesis combined the single component alkyl ammonium fluoride(TAAF)in CS-1 with different conventional organic solvents to design and prepare different types of new composite solvents with low viscosity.The solubility of TATB in composite solvents was studied,and the composite solvents with dissolving effect on TATB were selected.Based on the subsequent selection of recrystallization methods for regulating the morphology of TATB crystals,two composite solvent systems of CS-1/dimethyl sulfoxide(CS-1/DMSO)and CS-1/acetone(CS-1/AC)were selected.By changing the ratio of solvent component in the composite solvents,the effect of different solvent component on the solubility of TATB was further characterized by high performance liquid chromatography.The solubilities range from 8.91 to 149.02mg·m L^-1(CS-1/AC system)and range from 41.88 to 126.37 mg·m L^-1(CS-1/DMSO system),respectively,which provide the solvent basis for regulation of TATB crystal morphology.Through the characterization of the physical and chemical properties of the composite solvents,such as viscosity and density.The density changes slightly,and the viscosity decreases with the proportion of organic solvents increase,which provides a technical support for the regulation of TATB crystal morphology.2.Based on the new composite solvents,the regulation of TATB large crystals was studied.Due to the dense intra-molecular and inter-molecular hydrogen bond network structure of TATB,its solubility in most conventional solvents is extremely poor,so it is difficult to overcome the crystal habit that TATB is easy to grow into flake-like crystals through the regulation of solvents.In this thesis,based on the high solubility of TATB in new composite solvents and the characteristics of composite solvents,through the optimization of the type of composite solvents,the proportion of solvent components and the method of recrystallization,large TATB crystals were prepared by solvent evaporation at room temperature.200?m hexagonal crystals and 2-3 mm rod-like crystals were prepared respectively.Through the characterization of the structure and properties of different forms of crystals,the structure of hexagonal crystals are the same as raw TATB,and its purity is higher than raw TATB,indicating that large TATB crystal can be prepared by solvent evaporation method,and the purity of crystal can be improved,while the structure and properties of rod-like crystal are slightly different from raw TATB,which shows that rod-like crystal is a new type of composite crystal material containing TATB.3.In order to solve the problem of high energy but poor sensitivity of1,3,5,7-tetranittro-1,3,5,7-tetrazocane(octogen,HMX),based on the new composite solvents,solvent non-solvent induced self-assembly recrystallization method was used to combine nano-TATB and HMX to form TATB@HMX nano-composite grains.By changing the contents of TATB and HMX,TATB@HMX nano-composite grains with different TATB content were successfully prepared,and their doping,morphology,thermal properties,detonation properties and sensitivity were characterized.The TATB@HMX nano-composite grains are uniform spherical in size smaller than 100 nm,and the thermal properties are different from raw materials,with two thermal release peaks and two stages of mass loss,and the thermal properties of the two explosives influence each other.And it reduces the impact sensitivity of HMX while maintaining a high detonation velocity,indicating that the TATB@HMX nano-composite grains prepared by solvent non-solvent induced self-assembly is an effectively decreasing sensitivity strategy for high explosives and can meet the needs of high energy.