Microscopic kinetics of scission and reformation in the pyrolysis of nitrocellulose

Abstract

Nitrocellulose (NC) is essential in high-energy propellants, with nitrogen content affecting its pyrolysis rate and thermal stability. This study creates all-atom models of NC with varying nitrogen levels to explore pyrolysis mechanisms and validate them against experimental thermal response data. Results show that RO − NO₂ bond cleavage initiates NC decomposition. Lower nitration levels convert nitrogen oxides into carbon-nitrogen compounds, primarily HCN. Additionally, HCHO production is linked to CH₂ONO₂ group transformation, with low-nitration, high-hydrogen NC reducing HCHO yield. Kinetic parameters for cellulose thermal decomposition indicate that pyrolysis activation energies decrease with nitration levels, demonstrating that nitration significantly lowers the energy barrier for ring-opening. Molecular dynamics simulations reveal pathways for HCHO, NO₂, and NO generation during combustion, enhancing understanding of NC combustion mechanisms and safety in explosive applications.