Naslov
Dynamic Mechanical Properties of Artificially Aged Double Base Rocket Propellant and Possibilities for Prediction of their Service Lifetime

Autori
Matečić Mušanić, Sanja ; Sućeska, Muhamed

Izvornik
Central European journal of energetic materials (1733-7178) 10 (2013), 2; 225-244

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
ageing; double base rocket propellants; dynamic mechanical analysis; glass transition temperature; life -time prediction; loss modulus; softening temperature; storage modulus; tan delta

Sažetak
The ageing of double base (DB) rocket propellants, as a consequence of chemical reactions and physical processes that take place over time, has significant effect on their relevant properties, such as chemical composition and mechanical and ballistic properties. The changes of relevant properties limit safe and reliable service life of DB rocket propellants. Accordingly, numerous research efforts have been undertaken to find out reliable methods to measure the changes caused by ageing in order to assess the quality of DB rocket propellants at a given moment of their lifetime, and to predict remaining service lifetime In this work we studied dynamic mechanical properties of DB rocket propellant artificially aged at 80, 85 and 90°C temperature, in order to detect and quantify changes in dynamic mechanical properties caused by ageing, and to investigate possibilities for prediction of service lifetime. Dynamic mechanical properties were studied using a dynamic mechanical analyser (DMA). The obtained results have shown that the ageing causes significant changes of storage modulus (E´), loss modulus (E˝) and tan delta curves shape and positions. These changes are quantified by following some characteristic points on E´-T, E˝-T, and tan delta-T curves (e.g. glass transition temperatures ; storage modulus, loss modulus and tan delta at characteristic temperatures, etc.). It has been found out that the monitored parameters are temperature and time dependent, and that they can be shown as the functions of the so called “reduced time of artificial ageing”. In addition, it has been found out that on the basis of known changes of viscoelastic properties as a function of time and ageing temperature, and the known kinetic parameters of the ageing process, it is possible to calculate (determine) the change of the properties at any ageing temperature provided that the mechanism of ageing process does not change. Unfortunately, the use of kinetic parameters obtained by artificial ageing at high temperatures (above 60 °C) for the prediction of the propellant lifetime will not give reliable results, because the mechanisms of ageing at 85 °C and 25 °C are not the same.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Kemijsko inženjerstvo

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