Stabilizer Effect on Thermal Decomposition of Aged Solid Propellant

Density functional theory (DFT) is used to calculate and study the reaction mechanism of the four equations of nitrous oxide generation from plasticizer A3 (BDNPF: BDNPA=1 : 1). The optimal pathway is found for each equation, and finally, an optimal total pathway is found. At the same time, HONO is generated from A3 degradation. The stability is evaluated through ab‐initio molecular dynamics simulation (AIMD), and the electronic structure is analyzed to determine the active sites. The decomposition of A3 accelerates the aging of solid rocket propellant. Therefore, the mechanism of nitrous oxide generation from A3 can be revealed through various theoretical methods, which is of great significance for the subsequent slowing down of the aging of solid propellant.

Section: Introductionmentioning

confidence: 99%

Solid propellants: A first‐principles study of nitrous oxide generation from A3

Shen,

Yao,

Deng

et al. 2023

“…The presence of decomposition products (RÀ O, NO x ) and acid (HNO 3 ) speed up the degradation by attacking the yet undecomposed nitrate esters from NC in the propellant matrix [6]. Calorimetric tests revealed a loss of energy and an increase in temperature of the propellant, which has the effect of minimising its efficiency and reducing its lifetime [7][8][9][10][11][12]. To solve this issue, stabilisers are added to propellants.…”

Section: Introductionmentioning

confidence: 99%

Identification of the Degradation Products from α‐Tocopherol Used as Stabiliser in “Green” Propellants through its Lifetime

Damseaux

Scholl

Damblon

et al. 2022

Stabilisers are added to gun and rocket propellants to react with species responsible for nitrate ester degradation during storage. The degradation products can be toxic and therefore harmful. There is a need to replace such stabilisers by "green" molecules and to study their degradation patterns through ageing. Propellant powders must remain chemically stable for a minimum of ten years when stored at temperatures equivalent to 25 °C [1]. α-Tocopherol is a natural product that has been known for decades in other fields (Vitamin E) such as the pharmaceutical, food and cosmetics industries. It can act as a 'green' stabiliser" for smokeless powders because its heat flow is stable over time. In this paper, we characterise its stabilisation mechanism by identifying its main degradation products that could form within the propellant in an oxidising environment and in the presence of nitric acid. Liquid chromatog-raphy (LC) and gas chromatography (GC) separations are performed in order to dissociate the compounds formed during ageing. Compounds are then analysed by APCI-timsTOF to obtain the molecular ion masses and then perform fragmentation spectra (MS/MS) to characterise their structure. In addition, using preparative HPLC-UV, the degradation products are collected and analysed by NMR, with the aim of identifying the molecules. These identification methods help to unravel the stabilisation mechanism under accelerated ageing conditions. A time-related fluctuation of the degradation products amounts is also observed, which indicates that the decomposition products also have a stabilisation effect. The three major α-tocopherol degradation products are identified as: 2,3-epoxy-α-tocopherylquinone, 5,6-epoxy-α-tocopherylquinone and α-tocored.

“…A succession of secondary reactions like acid-base reactions, hydrogen abstractions and oxidations occur and produce gases such as CO, and especially NO and NO 2 [2,4]. These reactions have been studied using calorimetric tests which have revealed a loss of energy and an increase in temperature of the powder, which influences the performance of the propellant and reduces its lifetime [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Identification of the Degradation Products from α‐Ionone Used as Stabiliser in “Green” Propellants through its Lifetime

Damseaux

Scholl

Damblon

et al. 2021

A stabiliser is added to gun and rocket propellants to react with species responsible for degradation during decomposition. Propellant powder manufacturers and army personnel are confronted with toxicity during powder degradation and must replace current stabilisers with nontoxic molecules. According to the STANAG 4582 (North Atlantic Treaty Organization (NATO) Standardisation Agreement [1]), propellant powders must remain chemically stable for a minimum of ten years when stored at temperatures equivalent to an isothermal storage (25 °C). Single and double base smokeless powders with α-ionone as a "green" stabiliser are tested and the results show that the heat flow is stable over time and that the autocatalysis occurs 2 to 3 times later than in powders with conventional stabilisers. This stabiliser is efficient for all nitrate esterbased propellants. In the present paper, we identify and monitor the evolution of the main degradation products over time by nuclear magnetic resonance (NMR), mass spectrometry (MS) to unravel the stabilisation mechanism under accelerated aging conditions. A time-related fluctuation of their respective amounts (increasing then decreasing, then re-increasing, …) is observed, which indicates that the daughter products have also a stabilisation effect. The three major α-ionone daughter products are identified as: 3-oxo-α-ionone, 4-oxo-β-ionone and 4,5-epoxy-α-ionone.