The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced ...The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced sensitive co-crystals of high performance nitramine explosives like HMX and CL-20 with a relatively less insensitive explosive 1,1-diamino-2,2-dinitroethylene or FOX-7.Stronger intermolecurar hydrogen bonding in FOX-7 is responsible for limited solubility in nost of o rganic solvents.Large solubility differences of FOX-7 with HMX and CL-20 restricts ifs co-crystallization through classical methods that yields thermodynamically favorable product.Spray flash evaporation,a kinetic crystallization method,has been therefore adopted and could successfully produce CL-20/FOX-7(2:1) and HMX/FQX-7(4:1) co-crystals.The fine powdered materials obtained were characterized by SEM,powder XRD,Raman spectro scopy,DSC-TGA etc.Multipoint Raman spectra showed consistent occurrence of spectral features indicating stoichiometric co-existence of ingredients in the crystal lattices.DSC analysis showed absence of all thermally assisted solidsolid phase transformation in the co-crystals as they were observed in pristine materials.The thermal stability calculated in terms of activation barrier fordecomposition,revealed the CL-20/FOX-7 co-crystal to be interlediately stable on comparison to their constituents while,the HMX/FOX-7 co-crystal is more stable.Compared to pure HMX and CL-20,both the co-crystals have shown higher insensitivity to impact force,suggesting them to be suitable for future generation insensitive munitions.展开更多
Energetic materials pose challenges in preparation and handling due to their contradictory properties of high-energy and low-sensitivity.The emergence of co-crystal explosives is a new opportunity to change this situa...Energetic materials pose challenges in preparation and handling due to their contradictory properties of high-energy and low-sensitivity.The emergence of co-crystal explosives is a new opportunity to change this situation.If the co-crystal explosive is coated into spherical particles with uniform particle size distribution,this contradiction can be further reduced.Therefore,binder-coated hexanitrohexaazaisowurtzitane/2,4,6-trinitrotoluene(CL-20/TNT)co-crystal microspheres were prepared by droplet microfluidic technology in this work.The coating effects of different binder formulations of nitrocellulose(NC)and NC/fluorine rubber(F2604)on the co-crystal spheres were studied.The scanning electron microscopy(SEM)results showed that the use of droplet microfluidic technology with the above binders can provide co-crystal microspheres with regular spherical morphology,uniform particle size distribution and good dispersion.X-ray diffraction(XRD),fourier-transform infrared(FT-IR),differential scanning calorimetry(DSC)and thermo-gravimetric(TG)methods were employed to compare the properties of the co-crystal microspheres,raw material and pure co-crystal.The formation of CL-20/TNT co-crystal in the microspheres was confirmed,and the co-crystal microspheres exhibited better thermal stability than the raw material and pure co-crystal.In addition,the mechanical sensitivity and combustion performance of the co-crystal microspheres were further studied.The results showed that the co-crystal microspheres were more insensitive than CL-20 and pure co-crystal,and displayed excellent self-sustained combustion performance and theoretical detonation performance.This study provides a new method for the fast,simple and one-step preparation of CL-20/TNT co-crystal microspheres,with binder coating,uniform particle size distribution,and excellent performance level.展开更多
基金Defense Research&Development Organization(DRDO),India for financial support towards this study。
文摘The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced sensitive co-crystals of high performance nitramine explosives like HMX and CL-20 with a relatively less insensitive explosive 1,1-diamino-2,2-dinitroethylene or FOX-7.Stronger intermolecurar hydrogen bonding in FOX-7 is responsible for limited solubility in nost of o rganic solvents.Large solubility differences of FOX-7 with HMX and CL-20 restricts ifs co-crystallization through classical methods that yields thermodynamically favorable product.Spray flash evaporation,a kinetic crystallization method,has been therefore adopted and could successfully produce CL-20/FOX-7(2:1) and HMX/FQX-7(4:1) co-crystals.The fine powdered materials obtained were characterized by SEM,powder XRD,Raman spectro scopy,DSC-TGA etc.Multipoint Raman spectra showed consistent occurrence of spectral features indicating stoichiometric co-existence of ingredients in the crystal lattices.DSC analysis showed absence of all thermally assisted solidsolid phase transformation in the co-crystals as they were observed in pristine materials.The thermal stability calculated in terms of activation barrier fordecomposition,revealed the CL-20/FOX-7 co-crystal to be interlediately stable on comparison to their constituents while,the HMX/FOX-7 co-crystal is more stable.Compared to pure HMX and CL-20,both the co-crystals have shown higher insensitivity to impact force,suggesting them to be suitable for future generation insensitive munitions.
基金National Natural Science Foundation of China(Grant No.22005275)to provide fund for conducting experiments。
文摘Energetic materials pose challenges in preparation and handling due to their contradictory properties of high-energy and low-sensitivity.The emergence of co-crystal explosives is a new opportunity to change this situation.If the co-crystal explosive is coated into spherical particles with uniform particle size distribution,this contradiction can be further reduced.Therefore,binder-coated hexanitrohexaazaisowurtzitane/2,4,6-trinitrotoluene(CL-20/TNT)co-crystal microspheres were prepared by droplet microfluidic technology in this work.The coating effects of different binder formulations of nitrocellulose(NC)and NC/fluorine rubber(F2604)on the co-crystal spheres were studied.The scanning electron microscopy(SEM)results showed that the use of droplet microfluidic technology with the above binders can provide co-crystal microspheres with regular spherical morphology,uniform particle size distribution and good dispersion.X-ray diffraction(XRD),fourier-transform infrared(FT-IR),differential scanning calorimetry(DSC)and thermo-gravimetric(TG)methods were employed to compare the properties of the co-crystal microspheres,raw material and pure co-crystal.The formation of CL-20/TNT co-crystal in the microspheres was confirmed,and the co-crystal microspheres exhibited better thermal stability than the raw material and pure co-crystal.In addition,the mechanical sensitivity and combustion performance of the co-crystal microspheres were further studied.The results showed that the co-crystal microspheres were more insensitive than CL-20 and pure co-crystal,and displayed excellent self-sustained combustion performance and theoretical detonation performance.This study provides a new method for the fast,simple and one-step preparation of CL-20/TNT co-crystal microspheres,with binder coating,uniform particle size distribution,and excellent performance level.
