Crystal Structures of the Commonly Used Plasticizers Ethylene Glycol Dinitrate, Diethylene Glycol Dinitrate, and Triethylene Glycol DinitrateCharacterization and Discussion of Their Structural Behavior

Ethylene glycol dinitrate (EGDN), diethylene glycol dinitrate (DEGDN), and triethylene glycol dinitrate (TEGDN) are used as plasticizers in propellant mixtures and have been known for more than 100 years. Despite the industrial application and the long history of these compounds, the crystal structures of all three compounds, which are liquids at room temperature, have not been determined. Therefore, in this work, the crystal structures were examined by low-temperature X-ray diffraction, and thus, the bonding properties and crystal packing in the solid state could be compared and discussed for the first time. Furthermore, the compounds were characterized by nuclear magnetic resonance spectroscopy and infrared spectroscopy. The thermal properties were investigated by DTA (differential thermal analysis) measurements, and the experimental vapor pressures were measured with the chromatography-assisted transpiration method. The densities at room temperature (for the liquids) were measured by gas pycnometry, and the energetic properties were calculated using the EXPLO5 code. Moreover, a more in-depth analysis of the different sensitivities through discussion of the Hirshfeld surfaces, created based on their crystal structures, was performed to compare their sensitivities in the solid state