Physicochemical properties and thermal behavior of nitrocellulose granules with eutectic mixtures of stabilizers

Abstract

AbstractExaminations of two-component mixtures, namely: triphenylamine + centralite I (TPA + CI) and triphenylamine + akardite II (TPA + AkaII) were carried out using differential scanning calorimetry (DSC), which served to determine phase diagrams. Experimental data were described with NRTL model and eutectic points for both systems were determined. For TPA + CI system, they were equal to xEu,TPA = 0.2899, TEu = 62.9 °C, whereas for TPA + AkaII system they amounted to xEu,TPA = 0.7868, TEu = 117.5 °C. Granules contain mixtures of eutectic composition were obtained. The physicochemical and thermal properties of resultant single base granules were studied. The helium density of both granules was approx. 1.47 g cm−3, the average dynamic force amounted to 0.55–0.60 bar−1 s−1, and the calorific value ranged from 3060 to 3095 J g−1. Both granules should be chemically stable for 10 years of storage at 25 °C; they meet the requirements of STANAG 4582 standard. DSC analysis of decomposition processes was used to determine kinetic parameters and to adjust the chemical reaction model of nth order with autocatalysis (CnB). Reaction order ranged from 2.6 to 3.0, while the activation energy was similar (197–198 kJ mol−1). Based on examination of thermal properties, it was observed that both eutectic mixtures of stabilizers prevent the decomposition reaction more efficiently than the use of individual compounds as stabilizers.