Molecular simulation study of the stabilization process of NEPE propellant

Kong, Lingze; Dong, Kehai; Jiang, Aimin; Yang, Chuan‐Lu; Tang, Yanhui; Xiao, Yundong

doi:10.1016/j.dt.2022.06.001

Cited by 7 publications

(2 citation statements)

References 29 publications

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“…Therefore, to save computing power, the PEG model with a polymerization degree of 2 was chosen here as the object of study for the binder aging reaction. Sun et al [ 23 , 24 ] have carried out molecular simulations of nitration and H abstraction reactions of PEG by DFT. As the purpose of their study was different from this study, the simulations of nitration and H abstraction reactions had to be recalculated to facilitate comparison of the differences between different aging reactions of the matrix of NEPE propellant.…”

Section: Resultsmentioning

confidence: 99%

Molecular Simulation Study on the Aging Mechanism of NEPE Propellant Matrix

Kong¹,

Dong²,

Tang³

et al. 2023

Molecules

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Polyethylene glycols (PEG) and toluene diisocyanate (TDI) are often used as the main components of binders and curing agents in solid propellants, and their aging is an important issue in the storage and use of propellants. To study the aging behavior and aging mechanism of nitrate ester plasticized polyether propellant (NEPE) matrix during storage, the transition states of aging reactions of binder and curing agent were optimized at the (U)B3LYP/6-311G(d,p) level of theory, and the rate coefficients over the temperature range of 298–1000 K were calculated by CVT theory. The results showed that there were five kinds of aging reactions for binder, which included decomposition, nitration, H abstraction, oxidation, and crosslinking reactions. Among them, theenergy barriers of oxidation and H abstraction reactions were relatively low (79.3–91.2 kJ·mol−1) and the main reaction types of binder aging. The main aging reaction of curing agent was decomposition. Compared with the aging reactions of binder, the energy barriers of curing agent are higher (196.6–282.7 kJ·mol−1) and the reaction is more difficult to occur. By comparing the energy barriers and rate constants of different reactions, it is found that the aging of NEPE propellant matrix can be divided into two stages. In the first stage, the propellant matrix mainly undergoes H abstraction and oxidation reaction, and as the reaction proceeds, the products crosslink to form -O-O-, -C-C-, and -C-O-C- bonds. At this time, the long chain molecules of the propellant matrix crosslink, and the molecular weight increases. This stage corresponds to the rising stage of mechanical properties in the aging process of the propellant. In the second stage, the propellant matrix mainly undergoes decomposition and nitration, resulting in degradation, the reduction of molecular weights, and the appearance of holes and microcracks in the matrix. This stage corresponds to the decline of mechanical properties in the aging process of the propellant. The above simulation results are in good agreement with the aging experimental phenomena, revealing the microscopic mechanism of the changes in the macroscopic properties of NEPE propellant during the aging process, and providing a theoretical basis for the related research on the aging properties and anti-aging technology of NEPE propellant.

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Section: Resultsmentioning

confidence: 99%

Molecular Simulation Study on the Aging Mechanism of NEPE Propellant Matrix

Kong¹,

Dong²,

Tang³

et al. 2023

Molecules

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“…Molecular simulations were performed to improve the understanding of the stabilisation process of the nitrate-ester plasticised polyether propellant (NEPE) using Density Functional Theory (DFT). The simulations were of the reaction that generates nitrogen dioxide (NO 2 ), the autocatalytic and ageing reaction triggered by the NO 2 , and the absorption reaction of the stabilisers during the propellant stabilisation process [21].…”

Section: Introductionmentioning

confidence: 99%

Making Progress Towards « Green » Propellants – Part III

Dobson,

Folly,

Sarbach

et al. 2024

Propellants Explo Pyrotec

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Stabilisers are an integral part of a propellant composition. They are essential for ensuring the chemical stability of nitrate‐ester based propellants, preventing oxidation, chain scission and uncontrolled heat generation. Progress is being made, especially in Europe, with REACh legislation (1907/2006) to use more environmentally‐friendly compounds. New stabilisers with a greener environmental profile and producing less toxic daughter products have been investigated by several groups, and several compounds demonstrated even better performances – more chemical stability and therefore longer shelf lives than formulations with the currently‐used stabilisers. Additionally, the good efficiencies and lower toxicities of the daughter products of the “green” stabilisers are also evaluated. This paper is a continuation of our previous work and demonstrates that for industrially‐manufactured propellants, that the tests performed by four different entities validate the stability and compatibility of the propellants, investigated previously on a laboratory scale, providing the community with safer formulations for the environment and health.

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