In this paper, systems for which miscibility (hydroxyl-terminated polybutadiene-dioctyl adipate or HTPB-DOA) or immiscibility (HTPB-diethylene glycol dinitrate or HTPB-DEGDN) have been firmly established were used to test the usefulness of an atomistic molecular mechanics model. Two specific aspects were discussed: miscibility assessment of a plasticizer/polymer blend, and predictins of the enthalpy of vaporization. Simulations were carried out using Amorphous Cell and Discover packages of the Material Studio software using Compass force field for all calculations. A good afreement has been found for miscibility observations of blends, and for solubility parameter, density, and derived enthalpy of vaporization for pure substances. Therefore, the approach proposed in this work is a useful tool to provide insights on miscibility and properties of a given polymer/plasticiser blend. In addition, it is a promising technique to help in screening among several plastic bonded explosive (PBX) formulations prior to real experimental tests.