Study on the Curing Reaction Kinetics of HTPB-IPDI Binder System with TECH as catalyst by FT-IR Measurements

摘要

The hydroxyl terminated polybutadiene (HTPB) - isocyanates binder systems possess a unique combination of properties, including superior adhesion, excellent mechanical properties and outstanding low temperature performance, and have been widely used in solid rocket propellants and polymer bonded explosives(PBXs). The cure reaction between HTPB and diisocyanates (e.g., TDI, IPDI) in the castable PBXs plays an important role in the adjustment of process parameters as well as properties of explosive formulations. In this paper, FT-IR spectroscopy is employed to investigate the kinetics of the curing of HTPB and isophorone diisocyanate (IPDI) in the presence of a low toxic and low viscosity catalyst, stannous isooctoate (TECH) so as to searching for curing conditions at room temperature. The concentrations of the isocyanate groups (-NCO) characterized by FT-IR during the cure reaction with respect to time are recorded at different temperatures (35°C, 45°C, 55°C, 65°C, 75°C) and at constant stoichiometric ratio (r = n_([NCO]): n_([OH])= 1.0). The kinetic parameters, i.e., activation energy (E_a), pre-exponential factor (A), activation enthalpy (ΔH) and activation entropy (ΔS) for the cure reaction which is a second-order reaction, are calculated based on the data.