Synthesis and Characterization of Energetic Nitrate Ester Plasticizers Compatible with HTPB

Hydroxyl terminated polybutadiene (HTPB) is the most important and versatile binder used in the formulation of composite solid propellant. However, HTPB is an inert binder and immiscible with traditional energetic plasticizers. In this research, two types of energetic plasticizer, 2-ethylhexyl nitrate (2EHN) and 2-ethyl-2-buthyl-1,3 dinitrate propane (EBDP), which have C /-ONO2 ratio greater than 4 are synthesized and characterized by FT-IR and 1H NMR. Performance of these compounds as energetic plasticizer have been investigated by measuring their heat of decomposition, heat of combustion, glass transition temperature and heat of formation. In addition, the compatibility of the selected plasticizers with HTPB, have been evaluated by calculation of Hansen solubility parameter and measurement of glass transition temperature (Tg) by differential scanning calorimeter (DSC). Low value of miscibility parameter (Δδ) and appearance of a single glass transition Tg is a reason for miscibility of the plasticizer in HTPB and formation a homogeneous binder/plasticizer system. Furthermore, the viscosity measurement of resin in different weight percent of plasticizer have shown that the equal mixture of two plasticizers provide the best results for process ability of resin.