Elucidation of the interaction between ammonium perchlorate and hydroxyl-terminated polyether during co-pyrolysis

Oxidizers and binders are indispensable constituents of propellants, but the chemistry of their thermal decomposition remains ambiguous. This study elucidates the cross-interactions between ammonium perchlorate (AP, as an oxidizer) and hydroxyl‑terminated polyether (HTPE, as a binder) in their co-pyrolysis processes by using online single photoionization mass spectrometry and thermogravimetry-Fourier transform infrared methods. The results show that AP significantly promotes the thermal decomposition of HTPE and the formation of products such as light olefins (e.g., propylene and 1,3-butadiene), esters (e.g., ethyl formate), and especially ethers (e.g., tetrahydrofuran and 1,4-dioxane). In addition, the differences in the decomposition temperature ranges and product distributions during the whole thermal decomposition stage between the pure components (pure AP or HTPE) and the AP/HTPE composite components were compared in detail. Two reaction regimes related to the co-pyrolysis of AP and HTPE were proposed at the molecular level (i.e., the reactions between the polyether chain of the HTPE binder and the decomposition products HClO₄ and O₂ of AP). This work provides a theoretical basis for further understanding insensitive propellants.