Catalytic effect and mechanism of multiwall carbon nanotube on decomposition of glycidyl azide polymer-based composite propellant

Catalysts effectively enhance the thermal decomposition of Glycidyl Azide Polymer (GAP)-based composite propellants. Among these, multiwall carbon nanotube (MWCNT) exhibits significant potential due to their exceptional properties. This study systematically investigates the catalytic effect and mechanism of MWCNT on thermal decomposition of the quaternary GAP-based composite propellant and its constituents, employing thermal analysis techniques combined with first-principles simulations. Differential scanning calorimetry (DSC) and isothermal kinetic analysis demonstrate that MWCNT effectively catalyzes the decomposition of both the azido groups in GAP-based energetic thermoplastic elastomer (GAP-ETPE) and ammonium perchlorate (AP), ultimately promoting the decomposition of the propellant. Specifically: The apparent activation energy for the first-stage decomposition of azido group decreased from 189.02 kJ mol⁻¹ to 170.61 kJ mol⁻¹, the heat release from AP decomposition increased from 353.94 J g⁻¹ to 392.76 J g⁻¹, the total heat release of propellant decomposition increased from 3005.82 J g⁻¹ to 3274.38 J g⁻¹. Theoretical calculations reveal that MWCNT reduces the energy barrier of rate-limiting step during decomposition by 5.3 % for azido group and 51.2 % for AP, indicating more significant catalytic effect on AP. Electronic structure analysis of transition states demonstrates electron transfer from conjugated π-electron system of MWCNT surface to singlet nitrene and hydroxyl radical, suggesting that the catalytic ability originates from the electron-donation of MWCNT conjugated electron cloud to electron-deficient active species. This study elucidates the microscopic mechanism of MWCNT catalyzed decomposition of azido group, AP and related propellant from a theoretical perspective, providing theoretical guidance for its application in energetic materials.