1IntroductionIn the field of research and application of explosives, it is generallya ccepted that improving the power and reducing the sensitivity of explosives are often two opposingc haracteristics. Only an explosive with high energya nd low sensitivity can meet the application requirements adequately [1,2].I no rder to improve the performance of materials, cocrystalt echnology had been widely applied in the pharmaceutical field [3,4].N evertheless,s ince Levinthal patented the HMX/AP cocrystal explosivei n1 978 [5],t he cocrystal technology had not attracted extensive attention in the explosives arena. Nowadays, the technology of cocrystal explosives has been preliminarily researched. By cooling crystallization, Zhou obtaineda nu rea nitrate and RDX cocrystal explosive, whose explosionp erformance was superior to that of am ixtureo fu rea nitrate and RDX [6].T he HMX/ TATB cocrystal explosive wasd esigned based on crystale ngineeringa nd its crystals tructure was predicted using the polymorph predictorm ethodi namoleculard ynamics simulation by Wei [7].B ased on the research of Wei,S hen prepared the HMX/TATBc ocrystal explosive by as olvent/nonsolvent process [8].T he cocrystals tructures of HMX/NTO and HMX/NMPw ere designed using Monte Carlo simulations and first principle method by Lin [9,10].ACL-20/HMX cocrystale xplosive wasp repared by Andersonu sing the resonant acoustic mixing technology [ 11]. CL-20 and BTF cocrystale xplosive, which was prepared by Yang, was about 600 mminsize and its detonation power was predicted to be superior to that of BTF [12].B oth CL-20 and TNT were used to prepare the CL-20/TNT cocrystal explosiveb y Bolton and Yang, respectively [13,14].So far,t he cocrystal methods of explosivem ainly included solvent evaporation, cooling crystallization, solvent/nonsolvent crystallization, and resonant acoustic mixing crystal-lization. However,t he cocrystals size rangedf rom tens to hundreds of micrometers, which limited its application. It is generally accepted that ultrafine explosives possess better performance both in energy and sensitivityt han those in large size [15][16][17][18][19].I nt he aspect of highb urning rate, detonation rate and low criticald iameter,n ano or submicron explosivep articles are generally favored over the large particles [20][21][22][23].O nly little research is done on nano or submicrometer cocrystal explosives.The spray drying method had been used to prepare nano explosive using the high supersaturation in the rapid evaporation process and it had been used to prepare pharmaceutical cocrystals as well [24][25][26][27][28].B ased on this property of spray drying, nanoH MX/TNT cocrystals with high energy and low sensitivity were preparedi nt his paper.F urthermore, the structural characterization,t he formation reasons of cocrystals, impact sensitivity,a nd thermolysis of HMX/TNT cocrystals were investigated in detail.Abstract:C ocrystals of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane( HMX) and 2,4,6-trinitrotoluene (TNT) with high energy and low sensiti...

The solubility of cyclotetramethylene tetranitramine (HMX) in four ionic liquids (ILs): 1,3‐dimethylimidazolium dimethylphosphate ([Memim]DMP), 1‐butyl‐3‐methylimidazolium chloride ([Bmim]Cl), 1‐hexyl‐3‐methylimidazolium bromide ([Hmim]Br), and 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([Emim]BF4) was investigated. Nano‐HMX were produced particles by spraying [Hmim]Br solution into purified ice water. Finally, the particle size, morphology, crystal phase, impact sensitivity, and thermal decomposition properties of nano‐HMX particles were tested and analyzed. All four ILs could dissolve HMX to a greater or lesser extent in the temperature range from 20 °C to 80 °C. The solubility of HMX in [Hmim]Br at 80 °C is up to 0.7 g mL−1. Recrystallized HMX particles are of polyhedral or spherical shape and 40 to 130 nm in size. X‐ray diffraction indicated that nano‐HMX has a similar crystal structure as raw HMX (β‐form). Compared with raw HMX, the nano‐HMX particles have much lower impact sensitivity. However, they are easier to explode than raw HMX under thermal stimulus due to the lower peak temperature and activation energy.

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This study examined the hydrothermal aging mechanism of carbon fiber reinforced epoxy resin (CF/EP) composites in acidic, alkaline, salt solution, and deionized water (marked as Ac-CF/EP, Al-CF/EP, Sa-CF/EP, and De-CF/EP). The water absorption of carbon fiber reinforced epoxy resin composites followed a two-step process for all four aging mediums, including an initial Fickian diffusion and a subsequent long-term deterioration response. The carbon fiber reinforced epoxy resin composites were degraded more easily in a weak acidic solution due to the degradation of secondary amines and ether bond in an EP molecular chain, which was even degraded into methyl, ethyl, isopropyl, and bisphenol-A monomers. Long-term hydrothermal aging led to significant degradation of the CF/EP composites in all four mediums, the shear strength of the aged composites from small to large was Ac-CF/EP < Al-CF/EP < De-CF/EP < Sa-CF/EP < raw carbon fiber reinforced epoxy resin, which reduced the bending strength by 38.1%, 31.0%, 20.9%, and 11.5%, respectively, compared to the raw carbon fiber reinforced epoxy resin composites. The degradation of the EP matrix and irreversible interface damage caused by hydrothermal aging were considered the main reasons for the degraded mechanical properties of the carbon fiber reinforced epoxy resin composites. It is strongly recommended to apply a protective film on the surface of carbon fiber reinforced epoxy resin composites to reduce the possibility of interaction with humid air.