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1 Central European Journal of Energetic Materials

1 2018

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Influence of Bismuth Complex Catalysts on the Cure Reaction of Hydroxyl-terminated Polyether-based Polymer Bonded Explosives

Ou Y., Jiao Q., Yan S., Zhu Y.

Central European Journal of Energetic Materials

2018

Vol. 15, no. 1

131--149

The kinetics of catalyzed urethane-forming reactions of hydroxyl-terminated 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.