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Aluminum nanoparticle (nAl) has a promising application prospect in energetic materials (EMs) due to its high reactivity. However, some issues like agglomeration and oxide layers seriously affect its performances. To actualize the potential of nAl, perfluoroalkyl acids (PFAAs) with different molecular structures were introduced into nAl-based EMs for surface functionalization in the current work. The energy performances of nAl/PFAAs including flame propagation features and heat release were investigated in different atmospheres, and the related fluorine fixation ratio ( FF R) was also obtained. Results show that both the energy performances and the FF R were improved with the increase of the skeleton chain length and the fluorine content of PFAAs. Although the heat release is higher in air, FF R in air is apparently lower than that in N 2 . Possible reaction mechanisms were probed by the in-situ monitoring of the gaseous and condensed products from thermal decomposition. This reveals that the oxide layer was first corroded by carboxyl, and fluorocarbons were generated succeeded by the fluorination of exposed Al. The most reactive intermediates are CF x free radicals, which dominates the initial interaction.

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The kinetics of catalyzed urethane-forming reactions of hydroxylterminated polyether (HTPE) with toluene di-isocyanate (TDI) in the presence of bismuth complex catalysts was investigated by non-isothermal differential scanning calorimetry (DSC). Fourier transform infrared spectroscopy (FTIR) was employed to monitor the chemical interactions of relevant groups. The kinetic parameters, including the apparent activation energy (Ea) and reaction rate constants (k) at typical temperatures calculated by the Kissinger and Crane methods, were used to evaluate the catalytic activities of triphenylbismuth (TPB) and tris(3-ethoxyphenyl)bismuthine (TEPB). The variations of Ea were studied to obtain an insight into the consistency of catalytic mechanism for the bismuth complex catalysts. The viscosity build-up of HTPE-based polymer bonded explosive (PBX) slurry was then measured to verify the catalytic activity and the pot-life during an actual manufacturing process, which fitted with the kinetics of the catalyzed cure reaction. The cure process was evaluated by the hardness of the PBX grains maintained at a temperature below typical manufacturing conditions. The results showed that TEPB is an effective catalyst, reducing the Ea of the cure reaction and the manufacturing temperature and time with an acceptable pot-life. The mechanical, thermal characteristics and compatibility of the HTPE-based PBXs were also investigated. The results suggest that TEPB is compatible with HTPE-based PBXs and contributes to improving the mechanical properties and thermal safety.

A series of fluoroalcohol grafted hydroxyl-terminated polyether (HTPE) polyurethanes (PU) elastomers were synthesized by a two-step method. The reaction progress was investigated by chemical titration and Fourier transform infrared spectroscopy (FTIR). The glass transition temperature (Tg), mechanical properties, morphology, and thermal decomposition behavior were determined for the preliminary analysis of PUs; the oxidizability property was tested by the decomposition of PU/Al composites. The results of mechanical and morphology properties demonstrated that the mechanical strength of modified PU elastomers was effectively improved for microphase separation of the hard segment. The PU film with the optimized fluoroalcohol content shows excellent performance of 17.7 MPa (tensile strength) and 547 % (elongation at break) at room temperature. Analysis of the thermal behaviors suggests that the oxidation ability of the modified PU is enhanced by the strong electronegativity of fluorine. The oxidizing gas HF, CF x , released during fluoroalcohol decomposition reacts with the alumina shell, releasing internal reactive Al, which improves the activity of the aluminum. This study might provide a new idea for utilizing high-performance polymer binders in composite solid propellants and casting explosives.