Synthesis, characterization of energetic polymers

Abstract

Branched polymers are known to provide advantages in terms of viscosity and glass transition temperature over their linear analogues. This study investigates the potential of branched energetic polyurethanes as energetic binders for composite propellants. Such systems have not been explored as energetic binders yet. The highly branched polyurethanes were synthesized by the A2 + B3 approach, where A2 is the diisocyanate end modified energetic glycidyl azide polymer (GAP) diol and B3 is the trimethylol propane (TMP). Linear polyurethanes were synthesized by reacting A2 with 1, 4 butane diol. Both reaction systems were catalyzed by dibutyltin dilaurate (DBTDL). The molecular weights, intrinsic viscosities, glass transition temperatures, decomposition energies and thermal stabilities of the polymers were measured for both the branched and linear polymers and the properties compared. It was found that, the branched systems have lower glass temperatures compared to the linear analogues. This property will provide definite advantages on the low temperature mechanical properties of the branched energetic polyurethanes. The molecular weights of the branched polyurethanes were not high enough to produce observable changes in the intrinsic viscosities. The decomposition energies and thermal stabilities of the polyurethanes were found to be independent of the macromolecular architecture.