Study On Formulations And Performances Of FOX-7 Based Insensitive Booster Explosive

To solve the problem of higher sensitivity and lower safety of the allowable booster explosive（JH-14）,can not meet the technical requirements of insensitive munitions on the booster explosive.In this paper,based on study of the ways and means to achieve insensitivity of the booster explosive,compared the sensitivity,energy,thermal stability and technical maturity of several typical insensitive explosives,the choice of low vulnerability,high energy,more mature technology 1,1-diamino-2,2-dinitroethylene（FOX-7）as the main explosive for insensitive booster explosive.Polyethylene glycol（PEG）with high thermal conductivity and ethylene vinyl acetate copolymer（EVA）with excellent mechanical properties are used as composite binders.A series of FOX-7 based insensitive booster explosive formulations were simulated using molecular dynamics,quantum chemistry,and mesoscopic dynamics.FOX-7based insensitive booster explosive modeling powder was prepared by ultrasonic assisted solvent evaporation method,and the optimal formulation was determined by combining the results of simulation calculations with impact and friction sensitivities as criteria.The main performance of FOX-7 based insensitive booster explosive and JH-14 booster explosive was tested,and the results were analyzed theoretically.The main research of this paper is as follows:（1）In a comprehensive comparison of several typical insensitive explosives on the basis of sensitivity,energy,thermal stability and technical maturity,the choice of low vulnerability,high energy,more mature technology FOX-7 as the main explosive for insensitive booster explosive.The binding energy(E_bind),cohesion energy density（CED）,initiating bond length(L_max)distribution,mechanical properties,and radial distribution function（RDF）between four binders,PEG,EVA,copolymer of vinylidene fluoride and hexafluoropropylene(F₂₆₀₃),and butadiene rubber（BR）,and FOX-7 were calculated using the molecular dynamics method.The structure and the reduced density gradient function（RDG）between the binder and FOX-7 were analyzed by quantum chemical methods.The mesoscopic dynamics evolution of binder in FOX-7 system was analyzed by Meso Dyn method.The simulation results are as follows:The FOX-7/PEG system performed better than FOX-7/EVA,FOX-7/F₂₆₀₃ and FOX-7/BR in terms of E_bind,CED,L_max,intermolecular interactions and mesoscopic dispersion effects,indicating that this system has the best stability and the lowest sensibility;The E_bind,CED,L_max,mechanical properties,and intermolecular interactions of the system constructed by blending PEG and EVA in different proportions with FOX-7 were between FOX-7/PEG and FOX-7/EVA,where the mechanical properties were enhanced with increasing EVA content and other properties were enhanced with increasing PEG content;Different ratios of PEG/EVA blended systems showed comparable performance in terms of mesoscopic dispersion effect;Therefore,when the ratio of PEG:EVA is 1:1,it is the best binder in terms of overall performance as it can balance the suitable sensibility and excellent mechanical properties;By analyzing the mean square displacement of the binder and its binding energy with the solvent,the optimal preparation temperature was 70°C and the optimal preparation solvent was ethyl acetate.（2）Different formulations of FOX-7 based insensitive booster explosive were prepared by solvent evaporation method.The simulation results were verified based on the impact and frictional sensitivities of the booster explosive.The results of the combined simulations and experiments were used to determine the optimal formulation of FOX-7 based insensitive booster explosive as FOX-7/PEG/EVA=97/1.5/1.5,and the solvent used was ethyl acetate.（3）The test results are as follows:The impact and friction sensitivities of FOX-7 based insensitive booster explosive were 0%and 4%,respectively,compared to 48%and 36%for JH-14;5s explosion temperature of 285℃,while the JH-14 for 280℃;FOX-7 base insensitive booster explosive to the activation energy of 239.44k J·mol^-1,thermal decomposition peak temperature and thermal explosion critical temperature of 490.05K,491.71K,respectively,while the activation energy of FOX-7 explosives 222.93k J·mol^-1,thermal decomposition peak temperature and thermal explosion critical temperature of 476.25K,477.81K;Charge density of 96%TMD,FOX-7 based insensitive booster explosive and JH-14 detonation velocity of8401m·s^-1 and 8380m·s^-1,respectively;The response level of FOX-7 based insensitive booster explosive in the slow cook-off test is burning;FOX-7 based insensitive booster explosive in the shock wave action 50%explosion of the bulkhead thickness of 5.68mm,while the JH-14 is10.47mm;The compressive strengths of FOX-7 based insensitive booster explosive and JH-14are 14.12MPa and 11.79MPa,respectively;FOX-7 based insensitive booster explosive vacuum stability qualified,good internal compatibility,storage life of not less than 20 years.