CAB is a binder commonly utilized in CL-20-based mixed explosives.Based on the requirements of CL-20-based polymer bonded explosives in formability,safety,and detonation energy,we explored a hightoughness and low dosa...CAB is a binder commonly utilized in CL-20-based mixed explosives.Based on the requirements of CL-20-based polymer bonded explosives in formability,safety,and detonation energy,we explored a hightoughness and low dosage CAB binder system.CAB was subjected to different toughening modifications and the effects of the modified CAB binders on the bonding and coating of CL-20 crystals,as well as the formability,safety,and mechanical properties of CL-20-based polymer bonded explosive molding powder(MP)were evaluated.The changes in glass transition temperature(Tg)and mechanical properties of the modified binders were investigated using the molecular dynamics simulation at first.A series of modified binders with different molecular weights were then synthesized and characterized by FTIR,1H NMR,^(13)C NMR and SEC.The T_(g) and cross-sectional morphologies of the binder membranes were determined by DSC and SEM.The tensile properties of the binder membranes with different molecular weights and their mixtures with the plasticizer were evaluated at different temperature.With the optimized modified binder,CL-20/CAB and CL-20/CAB-g-PCL-3 MPs with the same plasticizer ratio and Cl-20/CAB-g-PCL-3 MP with a lower plasticizer ratio and higher CL-20 content were prepared and evaluated for the bonding and coating effects,crystal form,mechanical sensitivity and specific heat capacity(C_(p))by SEM,XRD,sensitivity testing and DSC,respectively.Their compressive strengths and splitting tensile strengths were measured at different temperature using a universal testing machine.Our work has provided a high-toughness and low-dosage binder system for CL-20-based MPs and offers a novel strategy to improve the formability,safety,and energy of CL-20 based polymer bonded explosives.展开更多
To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitro...To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force field.It is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the void.The degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro groups.The existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more significantly.Detonation has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by voids.The results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals.展开更多
The emergence of TKX-50,an energetic ionic salt with a high enthalpy of formation and low sensitivity,has opened a new path for the development of high-energetic,insensitive composite explosives.However,due to the poo...The emergence of TKX-50,an energetic ionic salt with a high enthalpy of formation and low sensitivity,has opened a new path for the development of high-energetic,insensitive composite explosives.However,due to the poor interfacial binding properties of TKX-50 with conventional binders,there is a lack of effective guidance for the design of TKX-50 based composite explosives.To address the above issues,the interactions between carboxymethyl cellulose acetate butyrate(CMCAB)and other binders with explosives TKX-50/HMX were compared using the molecular dynamics method.Based on the simulations,TKX-50/HMX/CMCAB-based polymer-bonded explosives(PBXs)were prepared with CMCAB as binder,which displays a high binding energy(Ebind)with TKX-50 and high cohesive energy density(CED),and the effect of TKX-50 content on the performance of PBXs was investigated.The physical properties of PBXs,specifically the morphology,mechanical sensitivity,and thermal conductivity,were analyzed by SEM,sensitivity apparatus,and thermal conductivity meter,respectively.The specific heat capacity(Cp)and non-isothermal decomposition temperature of PBXs were tested by DSC,and then the corresponding thermal kinetic parameters were analyzed to evaluate their thermal safety.The adiabatic thermal decomposition processes of PBXs were tested using an ARC instrument.The decomposition mechanism and kinetics were also explored to further analyze their thermal stability and thermal safety under adiabatic conditions.The computer code EXPLO5 was used to predict the detonation parameters of PBXs.The results showed that CMCAB and TKX-50 displayed favorable interfacial bonding properties,and TKX-50 can be bonded with HMX to form a molding powder with a desirable morphology and safety profile.The TKX-50 in PBXs effectively improves the mechanical sensitivity and thermal safety of PBX and has a significant effect on the detonation performance of PBX.This research demonstrates a novel method suitable for screening and investigating high-energetic insensitive explosive systems compatible with TKX-50.展开更多
Understanding the response of solid combustibles under high radiant fluxes is critical in predicting the thermal damage from extreme scenarios.Unlike the more moderate radiant fluxes in conventional hydrocarbon fires,...Understanding the response of solid combustibles under high radiant fluxes is critical in predicting the thermal damage from extreme scenarios.Unlike the more moderate radiant fluxes in conventional hydrocarbon fires,extreme events such as strong explosion,concentrated sunlight and directed energy can generate dynamic radiant fluxes at the MW/m^(2) level,creating a unique threat to materials.This study investigates the pyrolysis and spontaneous ignition behaviors of corrugated cardboard by using both experimental and numerical methods,under 10-cm dynamic high radiant fluxes ranging from 0.2 to 1.25 MW/m^(2) for 10 s.The spontaneous ignition process at dynamic high radiant fluxes was recorded and quantified.Two ignition modes were found at the critical radiant flux of 0.4 MW/m^(2),namely hot-gas spontaneous ignition and hot-residue piloted ignition.The latter is not the focus of this paper due to its extremely small probability of occurrence.The research reveals that the increase in flux intensity induces shorter delay times for both pyrolysis and ignition,lower ignition energy density,along with a corresponding rise in the critical mass flux and surface temperature at ignition moment.The simulation results are generally aligned with the experimental findings,despite some divergences may be attributed to model simplifications and parameter assumptions.The work contributes to a deeper insight into material behavior under extreme radiation,with valuable implications for fire safety and hazard assessment.展开更多
基金supported by"the Fundamental Research Funds for the Central Universities".
文摘CAB is a binder commonly utilized in CL-20-based mixed explosives.Based on the requirements of CL-20-based polymer bonded explosives in formability,safety,and detonation energy,we explored a hightoughness and low dosage CAB binder system.CAB was subjected to different toughening modifications and the effects of the modified CAB binders on the bonding and coating of CL-20 crystals,as well as the formability,safety,and mechanical properties of CL-20-based polymer bonded explosive molding powder(MP)were evaluated.The changes in glass transition temperature(Tg)and mechanical properties of the modified binders were investigated using the molecular dynamics simulation at first.A series of modified binders with different molecular weights were then synthesized and characterized by FTIR,1H NMR,^(13)C NMR and SEC.The T_(g) and cross-sectional morphologies of the binder membranes were determined by DSC and SEM.The tensile properties of the binder membranes with different molecular weights and their mixtures with the plasticizer were evaluated at different temperature.With the optimized modified binder,CL-20/CAB and CL-20/CAB-g-PCL-3 MPs with the same plasticizer ratio and Cl-20/CAB-g-PCL-3 MP with a lower plasticizer ratio and higher CL-20 content were prepared and evaluated for the bonding and coating effects,crystal form,mechanical sensitivity and specific heat capacity(C_(p))by SEM,XRD,sensitivity testing and DSC,respectively.Their compressive strengths and splitting tensile strengths were measured at different temperature using a universal testing machine.Our work has provided a high-toughness and low-dosage binder system for CL-20-based MPs and offers a novel strategy to improve the formability,safety,and energy of CL-20 based polymer bonded explosives.
基金supported by the National Natural Science Foundation of China (22275018)the Project of State Key Laboratory of Explosion Science and Technology (Beijing Institute of Technology)(Grant No.QNKT20-04)。
文摘To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force field.It is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the void.The degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro groups.The existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more significantly.Detonation has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by voids.The results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals.
基金supported by“the Fundamental Research Funds for the Central Universities”.
文摘The emergence of TKX-50,an energetic ionic salt with a high enthalpy of formation and low sensitivity,has opened a new path for the development of high-energetic,insensitive composite explosives.However,due to the poor interfacial binding properties of TKX-50 with conventional binders,there is a lack of effective guidance for the design of TKX-50 based composite explosives.To address the above issues,the interactions between carboxymethyl cellulose acetate butyrate(CMCAB)and other binders with explosives TKX-50/HMX were compared using the molecular dynamics method.Based on the simulations,TKX-50/HMX/CMCAB-based polymer-bonded explosives(PBXs)were prepared with CMCAB as binder,which displays a high binding energy(Ebind)with TKX-50 and high cohesive energy density(CED),and the effect of TKX-50 content on the performance of PBXs was investigated.The physical properties of PBXs,specifically the morphology,mechanical sensitivity,and thermal conductivity,were analyzed by SEM,sensitivity apparatus,and thermal conductivity meter,respectively.The specific heat capacity(Cp)and non-isothermal decomposition temperature of PBXs were tested by DSC,and then the corresponding thermal kinetic parameters were analyzed to evaluate their thermal safety.The adiabatic thermal decomposition processes of PBXs were tested using an ARC instrument.The decomposition mechanism and kinetics were also explored to further analyze their thermal stability and thermal safety under adiabatic conditions.The computer code EXPLO5 was used to predict the detonation parameters of PBXs.The results showed that CMCAB and TKX-50 displayed favorable interfacial bonding properties,and TKX-50 can be bonded with HMX to form a molding powder with a desirable morphology and safety profile.The TKX-50 in PBXs effectively improves the mechanical sensitivity and thermal safety of PBX and has a significant effect on the detonation performance of PBX.This research demonstrates a novel method suitable for screening and investigating high-energetic insensitive explosive systems compatible with TKX-50.
基金the Presidential Foundation of CAEP(Grant No.YZJJZQ2023008)the National Natural Science Foundation of China(Grant No.NSFC 12372342)for financial support of this work.
文摘Understanding the response of solid combustibles under high radiant fluxes is critical in predicting the thermal damage from extreme scenarios.Unlike the more moderate radiant fluxes in conventional hydrocarbon fires,extreme events such as strong explosion,concentrated sunlight and directed energy can generate dynamic radiant fluxes at the MW/m^(2) level,creating a unique threat to materials.This study investigates the pyrolysis and spontaneous ignition behaviors of corrugated cardboard by using both experimental and numerical methods,under 10-cm dynamic high radiant fluxes ranging from 0.2 to 1.25 MW/m^(2) for 10 s.The spontaneous ignition process at dynamic high radiant fluxes was recorded and quantified.Two ignition modes were found at the critical radiant flux of 0.4 MW/m^(2),namely hot-gas spontaneous ignition and hot-residue piloted ignition.The latter is not the focus of this paper due to its extremely small probability of occurrence.The research reveals that the increase in flux intensity induces shorter delay times for both pyrolysis and ignition,lower ignition energy density,along with a corresponding rise in the critical mass flux and surface temperature at ignition moment.The simulation results are generally aligned with the experimental findings,despite some divergences may be attributed to model simplifications and parameter assumptions.The work contributes to a deeper insight into material behavior under extreme radiation,with valuable implications for fire safety and hazard assessment.
