Study On Pressed Polymer Bonded Explosives Based On CBNT

5,5’-dinitramino-3,3’-bi[1,2,4-triazole]carbohydrazide salt（CBNT）,as a new kind of energetic material synthesized in recent years,has great development prospect due to its high energy and insensitive properties.However,due to the fact that its synthesis process has not yet achieved industrial production and poor crystal habit in production,it has not yet been applied in practice.Therefore,in order to enable CBNT to be used as pressed polymer bonded explosive,this paper mainly studies CBNT from two aspects:improving the crystal morphology of CBNT and the selection of binder.The main research contents and results are as follows:（1）According to the crystal cell structure of CBNT,the crystal morphology of CBNT in vacuum was calculated for the first time,and the important faces of CBNT crystal morphology were obtained,which were（020）,（011）,（10-1）and（110）,respectively.The polarity of each crystal face was analyzed and compared by the groups exposed on each crystal face.The results show that the stronger the polarity of the solvent and the crystal face,the stronger the interaction between them,and the easier it is to prevent the growth of the crystal face.The effects of eight solvents on the crystal morphology of CBNT such as dimethyl sulfoxide were calculated by modified attchment energy model.The results show that all solvents except dimethylformamide are beneficial to improve the morphology of CBNT in theory.（2）The solubilities of CBNT in solvents for improving its crystal morphology were investigated by laser dynamic method.According to the measurement results,solvent-nonsolvent method was determined to be the suitable recrystallization method for CBNT with dimethyl sulfoxide as solvent.The recrystallization experiments of CBNT were carried out.The effects of different nonsolvents,concentration of CBNT and stirring rate on the morphology of CBNT crystals were compared.The results showed that when the concentration of CBNT was low and stirring rate was high,the agglomeration of CBNT crystals with acetone as non-solvent was the least,and the morphology of CBNT crystals was more granular and lumpy.The ultrasonic assisted spray experiment of CBNT was further carried out under this crystallization condition,the obtained crystal morphology was mostly ellipsoid and spherical,and the surface was smooth,but the size of the crystals is not uniform.（3）Three kinds of high polymers F₂₃₁₁,F₂₃₁₄ and EVA were selected as the binder with the（020）crystal face of CBNT to construct the interface structure model,and the binding energy,the length of trigger bond,cohesive energy density,radial distribution function and mechanical properties of each model were calculated by molecular dynamics method.The results showed that the binding energy between three models and CBNT were F₂₃₁₄>F₂₃₁₁>EVA,indicating F₂₃₁₄ and CBNT has the better compatibility.The maximum bond length of the probable trigger bond（N-NO₂）decreased and the average bond length remained basically unchanged,indicating that the addition of binder reduced the sensitivity of the explosive to some extent.The addition of the three binders can improve the cohesion energy density of CBNT and make the system more stable,among them F₂₃₁₄ has the best effect.The radial distribution function analysis shows that there are hydrogen bond exists between the three kind of binder and the base explosives.In addition,in comparison with CBNT,the rigidity of PBXs is decreased and the ductility is enhanced.Among three binders,the improvement of F₂₃₁₁311 is the best.