The kinetics of the polymerization reaction of toluene diisocyanate with HTPB prepolymer

The uncatalysed and catalysed polymerization of a hydroxyl-terminated polybutadiene with toluene diisocyanate has been studied in toluene solution at four different temperatures. The rate constants (k₁, k₂) and the activation parameters (Ea₁, Ea₂, ΔS₁^?, ΔS₂^?) for the isocyanate groups in the 4 and 2 positions were calculated. It was found that the catalysts enhance the reactivity of the 2 position isocyanate group rather than the 4 position isocyanate group. It was also found that diethylcyclohexylamine has higher selectivity than dibutyltin dilaurate to enhance the reactivity of the isocyanate group in the 2 position. The effect of solvent has also been studied. The reactivity decreased in the following order; benzene = toluene > chlorobenzene > dioxane > nitrobenzene. © 1993 John Wiley & Sons, Inc.