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 (Tm) of 149.9 °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 Tm 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.