Study on the influence of ageing on thermal decomposition of double‐base propellants and prediction of their in‐use time

Abstract

A comparative study of the thermal decomposition of naturally and artificially aged double‐base propellants has been carried out at five different heating rates in a dynamic nitrogen atmosphere using differential scanning calorimetry (DSC) technique. The results show that there is only one decomposition peak on DSC curves, and this decomposition has been accelerated by ageing. The influence of the heating rate on the DSC behaviour of the propellants was verified. The kinetic parameters such as activation energy and frequency factor and the thermodynamic parameters such as the enthalpy of activation, free energy of activation and critical explosion temperature for the compounds were obtained from DSC data using non‐isothermal methods proposed by Kissinger and Ozawa. On the other hand, a prediction of the in‐service period by van't Hoff's equation was performed and compared with the experimental results in order to check the constancy and validity of this method. As a result, the prediction procedure used to obtain the time–temperature profile was achieved with good accordance. Copyright © 2012 John Wiley & Sons, Ltd.

Solid + liquid equilibria and molecular structure studies of binary mixtures for nitrate ester’s stabilizers: Measurement and modeling

“…In this context, within the last ten years, several studies have been carried out by our research group with conclusive and interesting results [3,[10][11][12].…”

“…where M is the mass molar (g/mol) of the pure compound and ρ its density (g/cm 3 ) measured at 298.15 K.…”

“…The procedure for DSC measurements is similar to those implemented in our research group for analogous mixtures [3,10,11]. It guarantees the quality and precision of the data as different heating and cooling rates, or isothermal periods, resulted in similar thermograms, without the appearance of unexpected thermal phenomena.…”

“…The measurements were made three times, where each one consisted of 10 measurement cycles, providing 10 data points. Measurement uncertainties for all the components were estimated to be less than ± 0.003 g/cm 3 whereas the uncertainty associated with the temperature of the density experiments was evaluated to be less than 0.07 K. For FTIR Analysis, samples were embedded in KBr pellets and analyzed by using a Shimadzu spectrometer 8400S. The spectra were recorded in transmittance mode in the range of 4000-600 cm −1 .…”

“…To ensure a safe life and long storage time under adverse storage conditions with acceptable chemical, thermal, mechanical and ballistic performances, such materials should contain various chemical compounds such as stabilizers [1]. Solid propellants consisting of nitrocellulose (NC) and/or other nitrate esters (NE), are inherently chemically unstable and tend to decompose even at the normal storage conditions because of the low bonding energy (155 kJ/mol) of the nitrate ester group (CH 2 -O-NO 2 ) [2][3][4]. They undergo slow decomposition and generate nitrogen oxides (NO X ) which react with the residual moisture present in the propellant and form nitrous and nitric acids.…”