engleski

Kinetics of nitrocellulose decomposition in artificially aged double base propellant

The ageing of double base rocket propellants (DB rocket propellants), which is a consequence of chemical reactions and physical processes that take place over time, has significant effect on their relevant properties (e.g. chemical composition, viscoelastic and mechanical properties, ballistic properties, etc.). The changes of relevant properties limit the safe and reliable service life of DB rocket propellants. This is the reason why the studying of processes and consequences (or effects) of ageing is so important. One of the most important consequences of DB rocket propellant ageing is reduction of the viscoelastic and mechanical properties as the consequence of reduction of nitroglycerine (NG) content and nitrocellulose (NC) mean molecular mass. In this paper we have studied kinetics of NC decomposition in artificially aged DB propellant. The kinetic parameters are obtained following NC mean molecular mass reduction by Gel Permeation Chromatography (GPC), during artificial ageing at elevated temperatures. It has been shown that the artificial ageing of DB propellant causes significant reduction of NC mean molecular mass, while significant changes start after 60 days of ageing at 90 °C. The activation energy obtained in this way equals 145.1 kJ mol-1, which corresponds to the values obtained by M. Bohn, as well as to our results for decomposition of NC at the accelerated decomposition stage, determined from isothermal thermogravimetric experiments for nitrocellulose propellant: 138.6 kJ mol-1, at 0.02<<0.25.

: activation energy; double base propellant; kinetics; kinetics of degradation; nitrocellulose decomposition

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