Impacts of titanium dioxide nanoparticles on thermal decomposition kinetics of nitrocellulose-based propellant as a bio-derived polymer

Abstract

The catalytic effect of titanium dioxide nanoparticles (n-TiO₂) on the thermal properties and the decomposition kinetics of the double-base nitrocellulose (NC)/nitroglycerin (NG)/diaminoglyoxime (DAG) propellants were verified by thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC) analysis techniques. There were no visible changes in the degradation peak of DSC traces (around 2–5 °C) after the addition of n-TiO₂ to the propellant. The thermokinetic and thermodynamic parameters of the propellants were computed using the equations of Ozawa–Flynn–Wall, Coats Redfern, Starink and Kissinger. The nanocomposites revealed the single-stage thermal decomposition mechanism while the control sample decomposed as two-stage mechanism. The composites containing 1% and 3% (by weight) of n-TiO₂ showed lower and higher E_a values compared to the pure sample, respectively. This exhibited the catalytic effect of n-TiO₂ on the decomposition process at 1% and 3% (by weight) of n-TiO₂. The lower values of self-accelerating decomposition temperature (T_SADT) and critical ignition temperature (T_b) for the nanocomposites imply their higher sensitivity compared to the pure propellant. The entropy and enthalpy of the decomposition processes increased after adding n-TiO₂ into the pure sample. The positive values of \(\Delta H^\ne\) and \(\Delta G^\ne\) confirmed that the processes are non-spontaneous. Moreover, the kinetic modeling methods showed that the presence of n-TiO₂ changes the mechanism functions and the kinetic equations of the thermal degradation.

Graphical abstract