Energetic Materials Frontiers最新文献

The rheological behavior of propellant slurries is crucial for ensuring the feasibility of the 3D printing process, controlling print quality, regulating performance, and simulating predictions. However, there have been relatively few prior studies on the rheological properties of composite solid propellant slurries at low temperatures, which hinders the application of 3D printing propellant technology under extreme temperature conditions. In addition, the use of 3D printing technology to manufacture propellants at low temperatures is advantageous for improving safety. This paper investigates the rheological properties of monodisperse systems with aluminum powder as a solid filler and end-hydroxy polybutadiene (HTPB) as the dispersed phase at low temperatures (−15∼10 °C). It explores the effects of solid content, temperature, and particle size on their rheological properties. Results show that the viscosity of the system in the range of −15∼10 °C increases exponentially with the decrease in temperature, and the viscosity at −15 °C increases by 616.90 % compared with that at 10 °C when the volume fraction (φ) of Al-1 is 35.8 %; the larger size of the particles the larger the viscosity is when the temperature and φ are the same, which is interpretes in terms of interfacial properties between the systems. The low-temperature correction factor is introduced into the Einstein-Roscoe equation to obtain the modified viscosity-volume fraction equation, and the correction factor is 0.0173, as evidenced by its excellent agreement with the experimental data.

Energetic materials are the energy materials used by weaponry to accomplish launch, propulsion, and destruction. However, during manufacture, storage and use, they may be damaged and form microcracks when subjected to external stimuli such as temperature, humidity and impact, which ultimately lead to changes in material properties. Self-healing materials can repair the damage through physical or chemical processes, restoring their properties and extending their service life. This paper reviews the classification of self-healing polymer materials, principles underlying technologies for room-temperature self-healing polymer materials, and the applications of these technologies in energetic materials. Furthermore, this study proposes several key directions for future research on the technologies and their applications in energetic materials.

Electrochemical synthesis serves as a green and efficient method with great application potential. However, it has not been extensively applied in the synthesis of energetic materials. Nitrogen-rich heterocyclic compounds, as a new generation of energetic materials, enjoy advantages such as eco-friendliness, high energy output, and excellent safety performance. This study reports the electrochemical cathodic synthesis of copper nitrotriazole [Cu(NTz)₂] using copper chloride and 3-nitro-1,2,4-triazole as a reaction substrate and triethylamine as a deprotonation agent. The obtained Cu(NTz)₂ comprises uniform spherical particles of nano lamellae. As the dosage of triethylamine increased from 50 μL to 150 μL, Cu(NTz)₂ gradually grew into compact solid spherical particles, significantly increasing the energy output. Notably, the heat release increased from 711 J g⁻¹ to 1301 J g⁻¹, accompanied by a significant positive elevation of ignition performance and peak combustion pressure in the process of confined combustion. This greatly boosted the energetic performance of Cu(NTz)₂. Moreover, Cu(NTz)₂ demonstrates insensitivity to electrostatic discharge (E₅₀＞225 mJ) and friction (FS＞360 N), suggesting excellent safety performance. Owing to its outstanding energetic and safety performance, Cu(NTz)₂ boasts great potential for application as pyrotechnic compositions, including military gas-producing and incendiary agents. Moreover, it has been corroborated that Cu(NTz)₂ can be applied as a micro ignitor.

Explosives, a type of energetic material (EM), face a high-pressure environment in the detonation process or under shock conditions. Determining their high-pressure behavior is critical to their explosion and safety. 1-Methyl-3,4,5-trinitropyrazole (MTNP), a carrier of melt-cast explosives, exhibits the potential for replacing trinitrotoluene (TNT). However, there is limited knowledge about its structural evolvement at high pressure. Using a diamond anvil cell (DAC), this study investigated the structural variation of MTNP through in situ high-pressure synchrotron angle-dispersive X-ray diffraction (ADXRD) experiments and Raman measurements. As evidenced by the results, MTNP underwent phase transition at 8.7 GPa and amorphization at 15.3 GPa due to high pressure. Through the analysis of first-principles calculations and Raman spectra, this study proposed the mechanisms behind the changes in MTNP at high pressure. Furthermore, this study systematically explored the structural evolvement of MTNP and the evolution of its weak intermolecular interactions at high pressure, gaining further understanding of MTNP's detonation and safety.

Polymorphism is universal in energetic materials (EMs), which is originated from the differences of molecular conformers and stacking mode. The polymorphic transition may lead to the change of crystal structure and properties of EMs. In this work, β-Hx₂TNBI·2H₂O (β-1) was successfully synthesized through solvent-induced conformational transition of Hx₂TNBI·2H₂O. From the perspective of quantum chemistry and molecular dynamics, the crystal stacking changes caused by different molecular conformations are discussed in detail, which leads to the properties difference of EMs. The results show that β-1 featured wave-like crystal stacking, making it less sensitive to external mechanical stimuli than α-Hx₂TNBI·2H₂O (α-1) (α-1: IS > 6 J, FS > 288 N; β-1: IS > 20 J, FS > 360 N). α-1 featured better the aromaticity, which gives it higher thermal stability than β-1 (α-1: T_d = 186 °C; β-1: T_d = 146 °C). Simultaneously, compared with β-1, α-1 has higher crystal density and detonation performance. This work provides a new and effective way to change the safety of EMs.

Recent years have witnessed significant advancements in methodologies and techniques for the synthesis of energetic materials, which are expected to shape future manufacturing and applications. Techniques including continuous flow chemistry, electrochemical synthesis, microwave-assisted synthesis, and biosynthesis have been extensively employed in the pharmaceutical and fine chemical industries and, gratifyingly, have found broader applications. This review comprehensively introduces recent advancements in the utilization of these emerging techniques, aiming to provide a catalyst for the development of novel green methods and techniques for synthesizing energetic materials.

To meet the requirements of explosives in military and civilian fields, researchers are committed to improving the comprehensive performance of explosives. The performance of explosive crystals can be significantly improved by regulating the structure and morphology of single-compound explosive crystals as well as compounding explosive crystals. According to the related research on explosive crystals at home and abroad from 2022 to now, the development of explosive crystal composites and single-compound explosives' crystal morphology, particle size, and crystal form regulation study were reviewed. The explosive crystal composites encompass both the complex consisting of a single-compound explosive and the complex consisting of two separate types of explosives. Simultaneously, the main problems encountered in the development of explosive crystals were also analyzed, such as the deficiency of systematic and broadly applicable regulation methods and theories. Finally, the future development direction of explosive crystal research was envisioned, with the aim of providing guidance for the production, handling, and application of explosives.

Although new-type energetic materials have been investigated extensively, there is a challenge on how to integrate energy density and mechanical properties of energetic materials simultaneously. Herein, a versatile approach was proposed to design energetic materials with high energy density, reactivity, and flexibility based on a bio-inspired strategy. By mimicking the “brick-and-mortar” structure within a natural nacre, the energetic film with alternative layers of polytetrafluoroethylene (PTFE) and boron (B) was successfully fabricated. The nacre-mimetic PTFE/B energetic film exhibited excellent reaction heat (4413.9 J⋅g⁻¹) and bright combustion flame, which may originate from the exothermic reaction mechanism between fluorine (F) and B. Even more remarkably, such PTFE/B energetic film revealed prominent mechanical flexibility reported for the first time. These findings indicate that the nacre-mimetic strategy provides an effective route to engineer energetic materials with high energy density, reactivity, and flexibility.