Synergistic catalytic effect of carboxymethyl chitosan-Co and ZIF-67 on enhancing the combustion and mechanical properties performance of ammonium perchlorate-based composite propellants

Solid combustion catalysts can enhance the combustion efficiency of composite solid propellants by regulating the decomposition kinetics of ammonium perchlorate (AP). However, excessive solid filler content will aggravate the dewetting phenomenon at the catalyst-binder interface, leading to a decline in mechanical properties. In this study, AP/CMC-Co/ZIF composites with a porous network carbon structure were prepared using the droplet method and solution method, achieving the optimization of the interface structure of the HTPB-based propellant. The three-dimensional hydrogel network formed by the cross-linking of carboxymethyl chitosan with Co 2 + is transformed into a porous carbon network after calcination. This porous carbon network can effectively load and disperse the catalytically active CoO generated by the decomposition of CMC-Co, promoting the combination of the LTD and HTD stages of AP, and reducing the high-temperature decomposition temperature of AP by 136.1 ℃. Meanwhile, to address the issue of low energy in the composite system, a high-energy nitrogen-rich substance-zeolite imidazolate framework (ZIF-67) was introduced. During the thermal decomposition process, it releases Co 3 O 4 , which can form a synergistic catalytic effect with CoO. Combined with its pore structure, it helps with gas diffusion and heat transfer, thereby further promoting the thermal decomposition of AP, with the heat release reaching 802.6 J/g. Applying AP/CMC-Co/ZIF to the HTPB-based propellant can enhance the ignition capability (62 ms) and burning rate (10.03 mm/s) of the propellant. Moreover, the -NH 2 and -OH functional groups on the CMC framework can form covalent cross-links with TDI, strengthening the interfacial bonding force between AP and the binder matrix, and alleviating the dehydration phenomenon of the propellant (ε b /ε m = 1.33). The research results indicate that AP/CMC-Co/ZIF has multiple enhancing effects on the performance of the propellant, opening up new prospects for the development of HTPB propellant with high combustion performance and excellent mechanical properties.