Assessment of Stability of Propellants and Safe Lifetimes

Abstract

The surveillance of gun propellants is basically performed either by an investigation into the thermal behavior of the propellant or by the determination of its remaining effective stabilizer content. Over the years it is shown that the surveillance of NC based gun propellants is necessary. NC based materials are intrinsically unstable, and can cause many accidents. Some accidents were caused by old unstable material, other ones were initiated by the extreme conditions during storage, like during expeditionary operations of military forces. And in quite a few cases it was a combination of these. Surveillance tests have changed over the years, and the last philosophy is to test the propellants as close as possible in comparison to the way they are stored [1] for this way of testing the Heat Flow Calorimetry (or microcalorimetry) method is the optimum. Older methods like the Abel heat test, Methyl Violet Test, Bergman‐Junk stability test, are test methods an analysis of the current status, without or very limited prediction behavior. Besides that the temperatures are relatively high, the measuring value is quite strongly dependent of the observer/operator. In general these tests are applied for propellants and sometimes explosives, although the general application worldwide (as far they are in use by countries) is propellants.

Differentiation of stabilized nitrocellulose during artificial aging: Spectroscopy methods coupled with principal component analysis

“…This result revealed the absence of undesirable interactions between NC and stabilizers (DPA and MENA). These findings corroborated the wide employment of DPA as NC stabilizer in industrial scale and provided new information for the use of MENA in new NC formulations . Nevertheless, the unaged NC/ANA is distant from other samples, which is caused by the presence of certain chemical interaction between NC and ANA, a conclusion that agreed with the above FTIR spectral results as well as with other compatibility tests carried out elsewhere .…”

New Insights on the Compatibility of Nitrocellulose with Aniline‐Based Compounds

“…Although a slow decomposition can occur even under normal conditions of temperature, pressure, and moisture, NC remains the most important nitrate ester that is widely utilized in gunpowders and solid propellant formulations [4][5][6]. Because of its chemical instability, such energetic component should contain some stabilizing agent to avoid a number of degradation phenomena that can lead to autocatalytic decomposition, self-heating as well as cook-off safety hazards, and consequently negatively affect both in-service time and reliability of the formulations [7][8][9]. The common stabilizers for nitrate esters-based energetic materials belong to anilinebased compounds such as diphenylamine (DPA), 2-nitrodiphenylamine (2-NDPA) and p-nitro-N-ethylaniline, (N-(2methoxyethyl)-p-nitroaniline (MENA), N,N'-diethyl-N,N'-diphenylurea (C1, EC, ethyl centralite), N,N'-dimethyl-N,N'-diphenylurea(C2, MC, methyl centralite) and N-methyl N',N'diphenylurea (AK-II) [10,11].…”

“…Excellent research works all over the world have focused on the synthesis of new aniline-based stabilizers [14,15], the understanding of the interactions occurred between them [16][17][18], and the evaluation of the stability and performance of related energetic formulations [2,7,8,13,14], but without sufficiently addressing an exhaustive investigation about the compatibility issues for such combinations. Consequently, a number of stabilizers did not satisfy the development of nitrate-ester based energetic materials.…”

Solid–Liquid Phase Equilibria, Molecular Interaction and Microstructural Studies on (N-(2-ethanol)-p-nitroaniline + N-(2-acetoxyethyl)-p-nitroaniline) Binary Mixtures

“…The consequence of instability could be catastrophic since the inherent instability of nitrate esters-based propellant leads to self-ignition. Likewise, the effects of nitrate esters decomposition may include alterations in the chemical, physical and ballistic properties [6,7].…”