Estimation of enthalpy of formation for energetic thermoplastic polyurethane elastomers by group additivity method

The enthalpies of formation for energetic thermoplastic polyurethane elastomers (ETPE) based on glycidyl azide polymer (GAP), poly glycidyl nitrate(PGN), poly bis-azidomethyl oxetane (PBAMO), poly(3-nitratomethyl-3-methyloxetane) (PNIMMO), bis-azidomethyl oxetane-azidomethyl methyl oxetane (BAMO/AMMO) copolymer as soft segments, diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI) as hard segments and butadiene (BDO) as chain extender were estimated by group additivity method. The results show that the enthalpies are affected by the different soft segment type, hard segement type and the hard segment contents. The enthalpies of formation of the ETPE reduce with the increasing of the hard segments contents. The enthalpy of formation of MDI based ETPE is higher than that of the other isocynates. The enthalpies of formation of azide polymers based ETPEs are higher than that of nitrate ester polymers. The estimated enthalpies data of ETPEs can help to design high energy propellants.