Exploring the effect of ammonium nitrate on the thermal stability and decomposition kinetics of dual nitrocellulose-nitrostarch-based energetic composites

Abstract

This study explores a dual-biopolymer-based energetic composite, emphasizing the synergistic effects achieved by combining nitrocellulose (NC) and nitrostarch (NPS) biopolymers with ammonium nitrate (AN), as an oxidizer. The optimal formulation for the AN@NC-NPS composite was determined through theoretical specific impulse (I_sp) calculations using CEA-NASA software. Comprehensive spectral and thermal characterizations were conducted, where FTIR analysis confirmed the effective integration of AN within the NC-NPS matrix, revealing distinctive absorption bands of nitrate esters and AN, indicating a strong chemical compatibility. TGA and DSC analyses demonstrated a two-stage thermolysis, attributed respectively to NC-NPS matrix and AN oxidizer, with a mutual catalytic effect between them, shifting the decomposition process to lower temperatures for both stages. Advanced thermo-kinetic analysis employing various isoconversional approaches enabled precise estimation of key kinetic parameters, including Arrhenius parameters (E_a, Log₁₀(A)) and the most probable decomposition mechanisms (g(α), f(α)/f(0.5)). The observed reduction in activation energy across both decomposition stages confirmed the role of AN in enhancing AN@NC-NPS reactivity, further supporting the synergistic catalytic effect revealed by the DSC findings.