Energetic Materials Frontiers最新文献

When subjected to complicated thermal alternation, the low thermal conductivity (k) of polymerbonded explosives (PBXs) will induce high thermal stress, which will undermine the safety and reliability of the explosives by causing cracks or damage. However, it has been proven to be a challenge to efficiently increase the k of PBXs due to the high interfacial thermal resistance (ITR) and intrinsic defects of their conductive nanofillers. By introducing AgNWs with a high aspect ratio into graphene, this study constructed a novel multi-dimensional high-k nanofiller composed of one-dimensional (1D) silver nanowires (AgNWs) and two-dimensional (2D) graphene, namely gra@AgNWs. The AgNWs decorated could remedy the intrinsic defects of graphene by passing through the interspaces within graphene nanosheets to form connections as bridges. Consequently, the k of energetic polymer composites increased significantly by 89% from 0.425 ​W ​m⁻¹ ​K⁻¹ to 0.805 ​W ​m⁻¹ ​K⁻¹ at ultralow filler loading of 0.5 ​wt%. Furthermore, the temperature gradients and thermal stress in the composite cylinder decreased significantly under complicated thermal changes owing to the enhanced k. As quantitatively demonstrated through the fitting of experimental data using a theoretical model, AgNWs significantly decreased the ITR, paving highways” for phonon transfer between adjacent graphene nanosheets. Hence an expected synergistic effect of heat transfer was produced in the composites. This study provides new insights into the design and preparation of highly thermally conductive composites.

The deuteration of energetic materials contributes to high signal-to-noise ratios (SNRs) in neutron diffraction, thus allowing the structures of energetic materials to be effectively investigated. This study developed the synthesis methods of deuterated energetic materials through chemical synthesis or newly developed one-pot H/D exchange. Using these methods, it synthesized nine deuterated energetic materials in a concise and low-cost manner: deuterated 1,3,5-triamino-2,4,6-trinitrobenzene (TATB-d₆, 1), 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX-d₈, 2), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX-d₆, 3), dihydroxylammonium 5,5′-bis(tetrazole-1-oate) (TKX-50-d₈, 4), nitroguanidine (NQ-d₄, 5), 1,1-diamino-2,2-dinitroethylene (FOX-7-d₄, 6), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105-d₄, 7), trinitrotoluene (TNT-d₃, 8), and 3-nitro-1,2,4-triazol-5-one (NTO-d₂, 9). Furthermore, the single crystals of HMX-d₈ (2) and RDX-d₆ (3) were obtained, and the α-, β-, γ-, and δ-polymorphs of HMX-d₈ (2) were prepared accordingly. The deuterated energetic materials were characterized and analyzed using infrared spectroscopy (IR), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), X-ray diffraction (XRD), and neutron diffraction. Besides, this study determined the decomposition activation energy (E_a), pre-exponential factor (A), decomposition rate constant (k), and critical explosion temperature (T_b) of TATB-d₆ (1), HMX-d₈ (2), and RDX-d₆ (3) via DSC experiments at different heating rates. The NMR and neutron diffraction data show that these deuterated energetic materials have high deuteration rates of more than 95%. The DSC and TG analyses indicate that the deuterated energetic materials exhibit slightly higher decomposition temperatures than their nondeuterated counterparts. Furthermore, neutron diffraction shows that the deuterated energetic materials feature high SNRs.

To accurately predict the detonation and safety performances of high-energy explosives, it is necessary to investigate their reaction mechanisms on different scales, which, however, presents a challenge due to the complex reaction kinetics of the explosives and a lack of experimental methods presently. This work introduces the time-resolved pump-probe experiments capabilities aiming at high-energy explosives based on large-scale laser facilities and presents the recent progress in research on the dynamic process of the explosives, obtaining the following understandings: (1) First, the micron-sized single-crystal 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) can be compressed to an overdriven detonation state at a laser facility, followed by the shock Hugoniot measurements of TATB; (2) Second, high resolution transient X-ray radiography makes it possible to achieve the dynamic imaging of the internal deformation, damage, and reaction dynamics of high-energy explosive under dynamic loading; (3) Third, the phase transformation and chemical reaction products of the shock-compressed explosives can be investigated using dynamic X-ray diffraction or scattering spectra; (4) Finally, the structural changes, molecular reactions, molecular bond cleavage, and intermediate product components of explosives under ultrafast pumping can be explored using ultrafast laser spectroscopy. Large-scale laser facilities can provide various flexible pump-probe methods, including laser shock loading, transient X-ray imaging, dynamic X-ray diffraction, and ultrafast spectroscopy, allowing a series of experiments to be carried out to evaluate different levels of ignitions from low-pressure to overdriven detonations. Furthermore, the facilities also enable in situ, real-time investigations of the internal deformation, phase transition, and ultrafast dynamics of explosives under dynamic loading at high spatial and temporal resolutions. The study of the reaction kinetics and mechanisms of high-energy explosives on microscopic-mesoscopic scales provides an efficient means to unravel the mystery of explosive reactions.