Curing kinetics of hyperbranched polyester (HBPE)/HTPB polyurethane IPN by FT-IR

Curing processes of pure HTPB polyurethane and HBPE/HTPB polyurethane IPN were determined by FT-IR at different temperature. The results show that the reaction of HTPB polyurethane and HBPE/HTPB polyurethane IPN all follows the second-order kinetic mechanism. But the reaction rate is enhanced when hyperbranched polyester is introduced. Their activation energies are 28.2 kJ/mol and 18.5 kJ/mol respectively. It is due to the HBPE has Amphiphilic structure which can compatibilizing HTPB and IPDI. Groups of NCO and OH enrich in the "core" part of HBPE. This "core" provides reaction place between NCO and OH, then makes the local concentration of NCO and OH increase, so the reaction rate rises.