Estimation of formation enthalpy of thermoplastic polyurethane binder for novel thermoplastic propellant

In order to calculate the specific impulse of novel propellant with thermoplastic polyurethane (TPU) synthesized as binder, method and data developed by Van Krevelen and Chermin together with the theory of cohesive energy of polymers, were applied to estimate the formation enthalpy of TPU. Relationship between formation enthalpy and content of hard segment of TPU was quantitatively obtained. Results of formation enthalpy of TPU were then adopted to calculate the energetic performances of TPU/aluminum/ammonium perchloride propellant system. Results show that specific impulse reaches the maximum value as 2.59 kN·s/kg when the system consists of 14% TPU, 62% AP, 24% Al.