Polymerization kinetics in propellants of the hydroxyl‐terminated polybutadiene–isophorone diisocyanate system

The copolymerization of a hydroxyl-terminated polybutadiene with isophorone diisocyanate in a propellant formulation has been studied. The kinetic rates for four different reaction temperatures have been measured both in gumstock and samples containing ammonium perchlorate. It is shown that the presence of ammonium perchlorate (up to 90% by weight) neither catalyzes nor retards the rate of binder polymerization. It is also shown that the polymerization follows an apparent second-order rate low with an activation energy of 9.8 kcal/mole.