The field of propellants has recently witnessed dynamic shift, including advancements in propulsion technology and a growing emphasis on the development of environmentally friendly propellants. Nitrate ester (NE) are extensively used in solid propellants, exhibiting chemical instability as they undergo decomposition reactions. Stabilization is a crucial aspect in propellant, ensuring the safety and reliable performance of energetic materials. Stabilizer plays a vital role in inhibiting or slowing down the autocatalytic decomposition reaction of propellants. In response to grow health and environmental concerns, there is a continuous effort to explore and evaluate green stabilizers designed to replace traditional stabilizers, which have been associated with adverse environmental impacts. Therefore, this study aimed to provide an overview of the current research carried out in the field of NE-based propellants, emphasizing the most significant work undertaken on green stabilizer materials for NE-based propellants. A comprehensive review of various environmentally friendly and low-toxicity stabilizers employed in propellants are presented, and their effects on the stability and shelf-life performance of NE-based propellants are discussed. Furthermore, this paper delves into the stabilization mechanisms of green stabilizers to mitigate decomposition reactions, thereby preventing unwanted side effects and ensuring long-term storage stability. Through a comprehensive review of recent developments, the manuscript highlights the successes and challenges associated with the incorporation of green stabilizers in NE-based propellants formulations. Finally, the review concludes by outlining future research directions and opportunities for innovation in sustainable and green stabilizers as well as key issues that need to be addressed and resolved. The comprehensive review and insights provided in this study contribute to the ongoing efforts in developing safer and more sustainable propellant technologies.
Nitrocellulose (NC)-based propellants have played a pivotal role in the development of energetic materials for both military and civilian applications. This review offers a comprehensive exploration of NC-based propellants, tracing their evolution from their historical origins as smokeless gunpowder to modern advancements. It discusses the chemical composition and classifications of NC propellants, along with continuous efforts to refine smokeless powder formulations through studies on smoke formation, residues, and additives. Modern techniques such as PCR-based detection and dynamic light scattering have enabled precise analysis of NC properties, including variations in the degree of substitution and molar mass, which allow for tailoring the chemical structure to meet specific performance needs. Special attention is given to the combustion dynamics of NC-based propellants, with an emphasis on reaction zones, performance characteristics, and optimization strategies that enhance their overall efficacy. The review also highlights the significant impact of nitrogen content, additives, and processing methods on the performance, stability, and safety of NC-infused propellants. While higher nitrogen content improves energetic output, it also increases surface cracking and gas production, necessitating the use of stabilizers and additives like Bu-NENA, copper compounds, and MgH2 to enhance flexibility, thermal stability, and reduce sensitivity to mechanical and thermal stimuli. Aging and environmental factors further influence burn rate variation, underscoring the need for tailored formulations. In terms of environmental sustainability, this review addresses safety considerations in handling and disposing of NC-based materials, focusing on innovations such as alkaline hydrolysis and NC recovery to mitigate environmental risks. Stabilizers and eco-friendly additives effectively prevent chemical degradation, reduce shock sensitivity, and enhance thermal stability. The review concludes with future research directions aimed at further improving the stability and safety of NC-based propellants, ensuring their continued relevance in modern applications.