Nano‐sized energetic co‐crystal consisting of the most powerful used military explosive 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane (CL‐20) and a typical insensitive explosive used in propellants nitroguanidine (NQ) was prepared by vacuum freeze drying method. Material studio 6.1 was used to simulate the hydrogen bonds between CL‐20 and NQ molecules. Scanning electron microscopy (SEM) was used to reveal the morphology and size of the product. Fourier Transform infrared spectroscopy (FT‐IR) and X‐ray diffraction spectrum (XRD) proved the formation of the co‐crystal at the molecular level. Differential scanning calorimetry (DSC) was employed to characterize the thermal behavior of the co‐crystal. The result of mechanical sensitivity test indicated the sensitivity was effectively reduced compared to neat CL‐20.
In this paper a new energetic co-crystal consisting of 1, 3,5,3,5, and nitroguanidine (NQ) was prepared using a vacuum freeze drying method. Scanning electron microscopy (SEM) revealed that the particle size was under 500 nm and the morphology was spherical. Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy suggest that hydrogen bonds exist between HMX and NQ molecules. Powder X-ray diffraction spectra (PXRD) indicated the product was different from the single components and their mechanical mixture. Thermal gravimetric analysis and differential scanning calorimetry (TGA/DSC) were employed to characterize the thermal behavior of the co-crystal and then the related thermodynamic parameters were calculated, which indicated that after co-crystallization the molecule of the co-crystal needed more energy to activate. The result of an impact sensitivity test indicated that the sensitivity was effectively reduced compared to neat HMX and the mechanical mixture. The density of the product was found to be 1.80 g cm À3 and the storage performance was also investigated.
a b s t r a c tBatch preparation of nano-HMX was achieved via a mechanical trituration method. The morphology and particle size of nano-HMX and raw RDX were characterized using SEM. Then nano-HMX was used in a formulation of composite modified double base propellant containing RDX. The method is to use nano-HMX to replace the RDX in the formulation by 10% gradually with the total mass content of RDX and HMX unchanged. The burning rate, mechanical sensitivity and mechanical property of propellant strands with different mass content of nano-HMX were tested. The results indicate that the 30% content of nano-HMX has the best comprehensive performance which can be used as an improvement of the existing formula. A possible mechanism of action was discussed.
An energetic co-crystal consisting of the most promising military explosive 2, 4,6,8,10,4,6,8,10, and the most well-known oxidant applied in propellants ammonium perchlorate has been prepared with a simple solvent evaporation method. Scanning electron microscopy revealed that the morphology of co-crystal differs greatly from each component. The X-ray diffraction spectrum, FTIR, Raman spectra, and differential scanning calorimetry characterisation further prove the formation of the co-crystal. The result of determination of hygroscopic rate indicated the hygroscopicity was effectively reduced. At last, the crystallisation mechanism has been discussed. Defence Science Journal, Vol. 67, No. 5, September 2017, pp. 510-517, DOI : 10.14429/dsj.67.10188 2017 STuDY OF AN ENERGETIC-OXIDANT CO-CRYSTAL: PREPARATION, CHARACTERISATION AND CRYSTALLISATION MECHANISM 511 to do differential scanning calorimetry (DSC) analysis. 2 mg -3 mg simple was weighed into alumina crucible each time. Test conditions were recorded with 20 mL/min nitrogen purge flow at 20 °C /min from 25 °C to 500 °C. SEM StudiesAs shown in Fig. 1, AP crystals tend to be spherical with rounded edges and corners, which particle size is approximately 100 μm. Raw CL-20 particles are more like irregular polyhedron with uneven size. However, CL-20/AP co-crystal, presenting cubo octahedron, varies greatly from the morphology of each single component. stretching respectively. However, these two bands shifted to 3209.30 cm -1 and 3054.41 cm -1 in the co-crystal. XRD CharacterisationThe XRD patterns of AP, CL-20 and co-crystal are presented in Fig. 5. The characteristic peaks of AP with 2θ-values of 19.52, 22.79, 24.00, and 24.75 are not present in the co-crystal pattern. In the case of CL-20, the characteristic peaks at 10.88°, 12.74°, 13.95°, 16.46°, 25.96° and 28.02° are not present in the co-crystal. However in the co-crystal, a new peak at about 12.06°, 13.67°, 27.49° and 41.75° formed after crystallisation. The result indicated that the pattern of the as prepared co-crystal differs enormously from each individual component. The appearance of the unique powder diffraction pattern is evidence for the formation of a new crystal. FT-IR SpectraThe FT-IR spectra of AP, CL-20 and co-crystal are as shown in Fig. 4 and 3281.29 cm -1 , respectively. Similarly, some characteristic absorption peaks of CL-20 also shift after crystallisation. Those phenomena may be caused by the hydrogen bond interactions involved in co-crystal formation which changes the symmetry characteristic. Raman SpectraThe Raman spectra of AP, CL-20 and co-crystal are presented in Fig. 5. Some characteristic peaks of AP and CL-20 are detected in the co-crystal from Micro-Raman spectroscopy (MRS). Similar to FTIR, some peak shift also take place for Raman spectra which can be attributed to intermolecular hydrogen-bonding. For example, AP has band at 3212.38 cm Thermal PropertyAs shown in Fig. 6, CL-20/AP co-crystal presents a unique thermal property which is different from single componen...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.