Ammonium dinitramide(ADN)is considered as a potential substitute for ammonium perchlorate in energetic materials due to its high density,positive oxygen balance,and halogen-free characteristics.However,its application...Ammonium dinitramide(ADN)is considered as a potential substitute for ammonium perchlorate in energetic materials due to its high density,positive oxygen balance,and halogen-free characteristics.However,its application has been severely limited because of its strong hygroscopicity,difficult storage,and incompatibility with isocyanate curing agents.In order to better bloom the advantages of the highly energetic and environment-friendly ADN in the fields of energetic materials,an in-depth analysis of the current situation and discussion of key research points are particularly important.In this paper,a detailed overview on the synthesis,thermal decomposition,hygroscopic mechanism,and antihygroscopicity of ADN has been discussed,its application in powdes and explosives are also presented,and its future research directions are proposed.展开更多
The fluidization behavior of nano and sub-micron powders belonging to group C of Geldart＇s classification was studied in a mechanically vibrated fluidized bed （vibro-fluidized bed） at room temperature. Pretreated a...The fluidization behavior of nano and sub-micron powders belonging to group C of Geldart＇s classification was studied in a mechanically vibrated fluidized bed （vibro-fluidized bed） at room temperature. Pretreated air was used as the fluidizing gas whereas SiO2. Al2O3, TiO2, ZrSi, BaSO4 were solid particles. Mechanical vibration amplitudes were 0.1, 0.25, 0.35, 0.45mm, while the frequencies were 5, 20, 30, 40 Hz to investigate the effects of frequency and amplitude of mechanical vibration on minimum fluidization velocity, bed pressure drop, bed expansion, and the agglomerate size and size distribution, A novel technique was employed to determine the apparent minimum fluidization velocity from pressure drop signals. Richardson-Zaki equation was employed as nano-particles showed fluid like behavior when fluidized. The average size of agglomerates formed on top of the bed was smaller than those at the bottom, Size distribution of agglomerates on top was also more uniform compared to those near the distributor. Larger agglomerates at the bottom of the bed formed a small fraction of the bed particles. Average size of submicron agglomerates decreased with increasing the frequency of vibration, however nano particles were less sensitive to change in vibration frequency. Mechanical vibration enhanced the quality of fluidization by reducing channeling and rat-holing phenomena caused by interparticle cohesive forces.展开更多
Improved controllability and energy density of ignition agents are of great significance for the devel-opment of energetic composite materials.In this study,droplet microfluidics and emulsification tech-niques were co...Improved controllability and energy density of ignition agents are of great significance for the devel-opment of energetic composite materials.In this study,droplet microfluidics and emulsification tech-niques were combined to prepare HNS/CL-20 composite microspheres with polyglycidyl azide polymer(GAP)as the binder.The influence of binder content on the morphology of microspheres was investi-gated,and the microspheres were characterized and tested for particle size,crystal structure,thermal decomposition,dispersibility,mechanical sensitivity,combustion behavior and detonation performance.The results showed that microspheres prepared with a binder content of 3%had higher sphericity and particle size uniformity.The microspheres retained the crystal structure of both HNS and CL-20(ε-type).Compared with raw HNS,the microspheres had higher apparent activation energy,better safety per-formance,and good dispersibility.The ignition experiments and detonation performance tests show that HNS/CL-20 composite microspheres have excellent ignition performance,obvious combustion flame,and significant energy release effects,which are expected to achieve high energy and high-speed response of the igniter,thus improving the ignition reliability in special environments or systems.展开更多
It is still a huge challenge to introduce effective crack-healing ability into energetic composites with a high oxidizer content.In this article,a poly(urea-urethane)energetic elastomer was prepared by the polycondens...It is still a huge challenge to introduce effective crack-healing ability into energetic composites with a high oxidizer content.In this article,a poly(urea-urethane)energetic elastomer was prepared by the polycondensation reaction of glycidyl azido polymer(GAP),isophorone diisocyanate(IPDI),and 2-aminophenyl disulfide(2-APD).In the poly(urea-urethane)elastomer structure,the hybrid dynamic lock,including multilevel H-bonds and disulfide bonds,not only provides abundant dynamic interactions and promotes chain diffusion,but also enhances physical crosslinking density.Such a unique design fabricated the energetic elastomer with robust tensile strength(0.72MPa),high stretchability(1631%),and outstanding toughness(8.95MJ/m 3)in the field of energetic polymers.Meanwhile,this energetic elastomer exhibited high self-healing efficiency(98.4%at 60°C)and heat release(Q=1750.46J/g).Experimental and theoretical results adequately explain the self-healing mechanism,particularly the role of azido units.The high-solid content(80wt%)energetic composites based on the energetic elastomer presented outstanding micro-defect self-healing(97.8%)and recycling without loss of mechanical performance.The development of smart energetic composites with excellent self-healing and recyclable ability provides a meaningful way for a wide range of applications in the field of energetic materials.展开更多
基金financially supported by the National Natural Science Foundation of China (Project No. 21805139, 12102194, 22005144 and 22005145)the Joint Funds of the National Natural Science Foundation of China (No. U2141202)+1 种基金Natural Science Foundation of Jiangsu Province (No. BK20200471)the Fundamental Research Funds for the Central Universities (No. 30920041106, 30921011203)
文摘Ammonium dinitramide(ADN)is considered as a potential substitute for ammonium perchlorate in energetic materials due to its high density,positive oxygen balance,and halogen-free characteristics.However,its application has been severely limited because of its strong hygroscopicity,difficult storage,and incompatibility with isocyanate curing agents.In order to better bloom the advantages of the highly energetic and environment-friendly ADN in the fields of energetic materials,an in-depth analysis of the current situation and discussion of key research points are particularly important.In this paper,a detailed overview on the synthesis,thermal decomposition,hygroscopic mechanism,and antihygroscopicity of ADN has been discussed,its application in powdes and explosives are also presented,and its future research directions are proposed.
基金the financial support received from Ontario Research Fund for this study
文摘The fluidization behavior of nano and sub-micron powders belonging to group C of Geldart＇s classification was studied in a mechanically vibrated fluidized bed （vibro-fluidized bed） at room temperature. Pretreated air was used as the fluidizing gas whereas SiO2. Al2O3, TiO2, ZrSi, BaSO4 were solid particles. Mechanical vibration amplitudes were 0.1, 0.25, 0.35, 0.45mm, while the frequencies were 5, 20, 30, 40 Hz to investigate the effects of frequency and amplitude of mechanical vibration on minimum fluidization velocity, bed pressure drop, bed expansion, and the agglomerate size and size distribution, A novel technique was employed to determine the apparent minimum fluidization velocity from pressure drop signals. Richardson-Zaki equation was employed as nano-particles showed fluid like behavior when fluidized. The average size of agglomerates formed on top of the bed was smaller than those at the bottom, Size distribution of agglomerates on top was also more uniform compared to those near the distributor. Larger agglomerates at the bottom of the bed formed a small fraction of the bed particles. Average size of submicron agglomerates decreased with increasing the frequency of vibration, however nano particles were less sensitive to change in vibration frequency. Mechanical vibration enhanced the quality of fluidization by reducing channeling and rat-holing phenomena caused by interparticle cohesive forces.
基金supported by National Natural Science Foundation of China(grant No.22005275).
文摘Improved controllability and energy density of ignition agents are of great significance for the devel-opment of energetic composite materials.In this study,droplet microfluidics and emulsification tech-niques were combined to prepare HNS/CL-20 composite microspheres with polyglycidyl azide polymer(GAP)as the binder.The influence of binder content on the morphology of microspheres was investi-gated,and the microspheres were characterized and tested for particle size,crystal structure,thermal decomposition,dispersibility,mechanical sensitivity,combustion behavior and detonation performance.The results showed that microspheres prepared with a binder content of 3%had higher sphericity and particle size uniformity.The microspheres retained the crystal structure of both HNS and CL-20(ε-type).Compared with raw HNS,the microspheres had higher apparent activation energy,better safety per-formance,and good dispersibility.The ignition experiments and detonation performance tests show that HNS/CL-20 composite microspheres have excellent ignition performance,obvious combustion flame,and significant energy release effects,which are expected to achieve high energy and high-speed response of the igniter,thus improving the ignition reliability in special environments or systems.
基金Joint Funds of National Natural Science Foundation of China,Grant/Award Number:U2141202National Natural Science Foundation of China,Grant/Award Numbers:12102194,21905084,22105103Natural Science Foundation of Jiangsu Province,Grant/Award Number:BK20200471。
文摘It is still a huge challenge to introduce effective crack-healing ability into energetic composites with a high oxidizer content.In this article,a poly(urea-urethane)energetic elastomer was prepared by the polycondensation reaction of glycidyl azido polymer(GAP),isophorone diisocyanate(IPDI),and 2-aminophenyl disulfide(2-APD).In the poly(urea-urethane)elastomer structure,the hybrid dynamic lock,including multilevel H-bonds and disulfide bonds,not only provides abundant dynamic interactions and promotes chain diffusion,but also enhances physical crosslinking density.Such a unique design fabricated the energetic elastomer with robust tensile strength(0.72MPa),high stretchability(1631%),and outstanding toughness(8.95MJ/m 3)in the field of energetic polymers.Meanwhile,this energetic elastomer exhibited high self-healing efficiency(98.4%at 60°C)and heat release(Q=1750.46J/g).Experimental and theoretical results adequately explain the self-healing mechanism,particularly the role of azido units.The high-solid content(80wt%)energetic composites based on the energetic elastomer presented outstanding micro-defect self-healing(97.8%)and recycling without loss of mechanical performance.The development of smart energetic composites with excellent self-healing and recyclable ability provides a meaningful way for a wide range of applications in the field of energetic materials.
