Hazardous Properties of Molten Ammonium Dinitramide

Ammonium dinitramide (ADN) has appeared as a promising oxidizer for green propellants and thereby a potential substitute for ammonium perchlorate, largely in use in composite propellants for tactical and strategic long‐range missiles. The novelty lies in replacing ammonium perchlorate with a chlorine‐free oxidizer less harmful to the health and environment. However, ADN is hygroscopic and can potentially react with other chemical components, which could be overcome by microencapsulating the particles. The simple coacervation method was tested herein to microencapsulate ADN with a membrane made of hydroxyl‐terminated polybutadiene as pre‐polymer and methylene diphenyl diisocyanate as the curing agent. The effect of polyamine bonding agents on the capsule formation was tested by adding 0.5 or 2 % of Tepan or Tepanol, whose efficacy to bond to ADN was confirmed by detecting ammonia release through infrared spectroscopy. The capsule membrane was examined by optical and scanning electron microscopy. The dissolution time and rate were the parameters adopted to quantify permeability in a straight dissolution test in water, which demonstrated that 0.5 % Tepanol can provide the most effective protection. The infrared spectroscopy indicated that 60 °C temperature for prolonged periods, normally experienced by propellants, does not chemically affect the capsules’ membrane but can turn it lumpy. In conclusion, these polyamine bonding agents can assist the capsule formation over ADN particles using the simple coacervation method, however, their functionality on mechanical properties of propellants needs to be substantiated in forthcoming works as well as the effect of the concentration of bonding agents on propellant formulations.

Section: Methodsmentioning

confidence: 83%

Microencapsulation of ADN with HTPB‐based membrane in the presence of the bonding agents Tepan or Tepanol**

Silva,

Cardoso,

Diniz

et al. 2024

“…The sensitivity threshold of solid ADN powder is 3 to 5 J, but that of liquid ADN is less than 0.25 J. Thus, liquid ADN is as sensitive as nitroglycerin (<0.25 J), and the handling of molten ADN is dangerous [41]. Therefore, it is necessary to pay attention to the required safety procedures in the experimental operation of melt prilling methods.…”

Section: Prilling Technologymentioning

confidence: 99%

Anti‐hygroscopicity technologies for ammonium dinitramide: A review**

Tian

Zhao

Chen

et al. 2023

Valuable propellants have the characteristics of high impulse, low pollution, and strong stability, and oxidizers play a substantial role in determining the performance of propellants. Ammonium dinitramide (ADN) is a relatively promising oxidizer due to its high‐energy and chlorine‐free characteristics. However, although ADN exhibits high energy performance compared with traditional oxidizers, the high hygroscopicity of ADN when exposed to high humidity restricts its broader application in solid propellants. This review highlights the necessity of utilizing anti‐hygroscopicity strategies with ADN to extend its application. The anti‐hygroscopicity mechanism of ADN is summarized by calculations and experimental results. Anti‐hygroscopicity technologies that can be used with ADN include prilling, surface coating, and co‐crystallization, and these technologies are comprehensively summarized herein. This review is intended to provide insight into the use of anti‐hygroscopicity technologies with ADN, highlight the challenges of these methods, and point out future development directions.

“…By contrast with pure ADN, a transition from deflagration to detonation is always observed in the loose powders of ADN/RP and ADN/TH mixtures (Table 4). The heat released by the oxidation of the fuels, has a determining influence on the transition to detonation of these compositions, owing to the strong sensitization of ADN in molten state [32].…”

Section: Detonation Properties Of Adn-based Mixturesmentioning

confidence: 99%

New Detonating Compositions from Ammonium Dinitramide

Comet

Schwartz

Schnell

et al. 2021

Self Cite

This article reports on a new family of detonating compositions in which ammonium dinitramide (ADN) is used as an explosive oxidizer, and red phosphorus (P r ) or titanium hydride (TiH 2 ) as fuels. At optimized ADN/fuel ratios, these compositions have typical explosion heats higher than 7 kJ/g, detonation velocities in 3 mm diameter tubes ranging from 1.2 to 2.0 km/s at~40 % of their theoretical maximum density, with a run to detonation distance between 20 and 40 mm. Both compositions are insensitive to electrostatic discharge, but are very sensitive to impact and friction, ADN/P r mixtures being the most sensitive to these stress. The shockwave released by the reaction of these materials, efficiently initiates the detonation of high explosives such as pentaerythritol tetranitrate (PETN) or hexogen (RDX). In view of these characteristics, ADN-based detonating compositions must be considered as "green" substitutes for primary explosives containing heavy metals.