Combustion Properties of Amino‐Substituted Guanidinium 4,4′,5,5′‐Tetranitro‐2,2′‐biimidazolate(N4BIM) Salts

This paper describes the combustion properties of the amino‐substituted guanidinium 4,4′,5,5′‐tetranitro‐2,2′‐biimidazolate (N4BIM) series, including the bis‐mono, di and triaminoguanidinium salts. These salts are of interest as propellant ingredient additives, and in particular, the bis‐triaminoguanidinium salt of N4BIM displays excellent burn rate and combustion behavior. Our combustion studies have shown that TAGN4‐BIM displays a fast burning rate and has the lowest pressure dependence exponent yet measured for a triaminoguanidinium salt.     

Combined evaluation of nitrocellulose-based propellants: toxicity,performance, and erosivity

ABSTRACT

New formulations of nitrocellulose-based propellants were evaluated aiming less-toxicity-and-less-erosivity. Three original ingredients of M-14 propellant – dinitrotoluene, dibutyl phthalate, and diphenylamine – were replaced. The new formulations, with ballistic performances similar to M-14, were based on ethylcentralite, akardite-II, RDX, diethylene glycol dinitrate, triethylene glycol dinitrate, and acetyl tributyl citrate (ATBC). The toxicities of the crude ingredients were analyzed. The H₂ content in the combustion products was a key point in the analysis. The best results were found to the compositions based on ATBC and akardite-II only. The work can be used to guide future works related to new formulations of propellants.     

火药实用燃烧定律

本文应用概率论知识,通过对不同类型、不同口径以及不同药形和不同装药结构的枪炮,进行了大量的分析计算,建立了火药实用燃烧定律.在此基础上,给出了一般炮和无后座炮四种内弹道解法。并通过对多种枪炮内弹道正面问题的计算验证,证明该定律理论计算与射击结果是符合的。     

Synthesis and Characterization of Glycidyl Azide‐r‐(3,3‐bis(azidomethyl)oxetane) Copolymers

Glycidyl azide‐r‐(3,3‐bis(azidomethyl)oxetane) copolymers were synthesized by cationic copolymerization of epichlorohydrin and 3,3‐bis(bromomethyl)oxetane, using butane‐1,4‐diol as an initiator and boron trifluoride etherate as a catalyst, followed by azidation of the halogenated copolymer. The main objective of this work is the preparation of an OH‐terminated amorphous polymer with energetic content higher than that of the well‐known glycidyl azide homopolymer. The effect of experimental conditions, i.e., the rate of monomer feeding, on the final molecular weight and functionality of the copolymer has also been investigated. The obtained copolymers were extensively characterized to determine their composition and thermal stability. The heat of reaction for the polymerization of the halogenated key precursors has also been measured. It was found that even though both the operating conditions and the catalytic system were chosen in order to favor a living character of the polymerization, the final product seems to be the result of a combined living and active chain end mechanism. In particular, the latter is responsible for the formation of oligomers and not hydroxyl‐terminated chains. Nevertheless, the average number of OH groups is high enough to allow a cross‐linking of the polymeric chains, by addition of polyisocyanates and subsequent formation of inter‐chain urethanic bonds.     

Polynitrocubanes: Advanced High‐Density,High‐Energy Materials

More powerful and less shock‐sensitive explosives are continually being sought for both military and commercial use. Here the qualities a potential candidate must possess to make a good explosive are detailed, and the synthesis of octanitrocubane—a very promising candidate—is described. The physical properties of the nitrocubanes synthesized are also summarized and a proposal for the future is made.     

Synthesis and Energetic Properties of Bis‐(Triaminoguanidinium) 3,3′‐Dinitro‐5,5′‐Azo‐1,2,4‐Triazolate (TAGDNAT): A New High‐Nitrogen Material

This paper describes the synthesis and characterization of bis‐(triaminoguanidinium)‐3,3′‐dinitro‐5,5′‐azo‐1,2,4‐triazolate (TAGDNAT), a novel high‐nitrogen molecule that derives its energy release from both a high heat of formation and intramolecular oxidation reactions. TAGDNAT shows promise as a propellant or explosive ingredient not only due to its high nitrogen content (66.35 wt.‐%) but also due to its high hydrogen content (4.34 wt.‐%). This new molecule has been characterized with respect to its morphology, sensitivity properties, explosive, and combustion performance. The heat of formation of TAGDNAT was also experimentally determined. The results of these studies show that TAGDNAT has one of the fastest low‐pressure burning rates (at 6.9 MPa) measured till date, 6.79 cm s⁻¹ at 6.9 MPa (39% faster than triaminoguanidinium azotetrazolate (TAGzT), a comparable high‐nitrogen/high‐hydrogen material). Furthermore, its pressure sensitivity is 0.507, a 33% reduction compared to TAGzT.     

Review on Energetic Thermoplastic Elastomers (ETPEs) for Military Science

Energetic thermoplastic elastomers (ETPE) are futuristic binders for propellant/explosive formulations. Various aspects of ETPEs are addressed in this review. Synthesis modes of different copolymers for ETPEs are discussed. Attention is also given to formulations and thermal studies of ETPE‐based propellants and explosives. Processing methods and parameters of composition are included. As the cost and environmental concerns are prime factors of future generation propellants/explosives, the recovery and reprocessing methods are also briefly discussed.     

Ion Chromatographic Analysis of Ammonium Dinitramide–Oxidizer for Propellant and Pyrotechnic Applications

Analysis of ammonium dinitramide (ADN), the advance rocket propellant oxidizer, in pure form as well as in mixtures was carried out by ion chromatography (IC). The purity of ammonium dinitramide was directly determined by estimating the dinitramide ions and indirectly by estimating the impurities. Both methods gave results comparable with those determined by Differential Scanning Calorimetry and UV spectroscopy. The chemical composition of ADN in mixtures containing nitrate, chromate, chlorate, perchlorate, and thiocyanate ions was quantitatively estimated in the same solution without any interferences or prior separation of analyte ions. The newly developed ion chromatographic methods for the analysis of ADN are simple and fast with good accuracy and precision when compared to other analytical techniques. The IC methods are found to be highly suitable for quality control analysis of ADN containing compositions and for the online process monitoring of the formation of ADN in the reaction mixture.     

Lead Free Ammunition without Toxic Propellant Gases

Environmental and health considerations have encouraged the development of ammunition with substitutes for lead and other heavy metals. In general, the emission products from munitions containing nitro‐based propellants are highly complex mixtures of gases, vapors, and solid particles. The major combustion products are H₂O, CO, CO₂, H₂, and N₂. In addition, compounds including hydrogen cyanide (HCN), ammonia (NH₃), methane (CH₄), nitrogen oxides, benzene, acrylonitrile, toluene, furan, aromatic amines, benzopyrene, and various polycyclic aromatic hydrocarbons are detected in minor concentrations. Many of the identified chemical species have severe toxicological properties, and some of the compounds do even have mutagenic effects. Gun smoke emission is a concern because its exposure to humans may be substantial during military and civilian police training, as respiratory protection equipment is not routinely worn. In this work we study the compositions of some of the main decomposition products, experimentally as well as theoretically. The concept of frozen equilibrium at around 1500–2000 K appears to apply for CO, CO₂, and H₂. However, the trace species in the combustion mixtures appear theoretically to be present in negligible concentrations. Our measured results are many orders of magnitude higher than theoretical results in open space. We forecast that future development of gun powder will focus on reducing the amount of toxic trace species.     

Triphenylamine – a ‘New’ Stabilizer for Nitrocellulose Based Propellants – Part I: Chemical Stability Studies

Triphenylamine (TPA) was used for the first time in France in 1937 as a stabilizer for propellants. The stability of those samples was described as ‘good’. Around 1950 an American group produced TPA stabilized propellants and investigated the decomposition mechanism. Apart from one single experiment in the 1970s no further attempts were made to take TPA as a stabilizer for propellants.