Unrevealing the role of the sulfonitric media composition on the design and properties of potato starch-based nitrogen-rich biopolymer

Abstract

In research of crafting high-energy materials from sustainable sources, this study undertook the synthesis of energetic nitrostarches employing diverse sulfonitric mediums to better assess how they influence the characteristics and performance of potato starch nitrate. Accordingly, a deep exploration of the physicochemical properties, morphology, heat behavior, mechanical sensitivities, and combustion energy of starch nitrate was carried out. The experimental results highlighted that an increase in the nitric acid concentration from 70% to 100% enhanced the density (≥1.71 g/cm3) and the crystallinity of potato starch nitrate, whereas the nitrogen content does not exhibit any evident correlation. Moreover, its short-term stability remains unaffected as a function of nitric acid content, in contrast to the long-term stability together with mechanical sensitivities (Impact Sensitivity ≥ 4 J; Friction Sensitivity ≥ 252 N) that decrease with nitrogen content. The investigation of the thermolysis kinetics of starch nitrate demonstrated a decrease in the activation barrier (Ea) with the increase in nitrogen content. The Ea of high nitrogen content potato starch nitrate is inferior to that of cellulose nitrate, proving the enhanced reactivity of starch nitrate. These findings demonstrated that the elaborated nitrogen-rich potato starch biopolymers display promising features that support their use in high-performance propellant or explosive formulations.