Thermal behavior and microstructure of a Methylnitroguanidine-Nitroguanidine energetic eutectic

To shed light on the structure-property relationship of a methylnitroguanidine (MeNQ)-nitroguanidine (NQ) eutectic, its thermal behavior and microstructure were studied by various techniques. The eutectic composition of MeNQ-NQ with the lowest melting temperature (T-m) of 149.9 degrees C was at the mole ratio of 7 : 3, as determined by temperature-composition (T-X) and melting enthalpy-composition (H-X) diagrams. The MeNQ-NQ eutectic exhibited a homogeneous network structure composed of the plate-shaped MeNQ and acicular NQ enriched phases that resulted in a uniform melting around the T-m observed by in situ variable temperature optical microscopy. The X-ray diffraction from MeNQ-NQ eutectic showed peaks that were shifted to low scattering angle, an indication of the expansion of its crystal lattice and the formation of solid solutions. Small-angle X-ray scattering from the sample showed a rough interface between the MeNQ- and NQ-enriched phases. Infrared spectral data showed absorption peaks due to -NH2 and -CH3 groups that were red shifted relative to the raw materials, an indication of hydrogen bond interactions between MeNQ and NQ molecules.