Fabrication and properties of glycidyl azide polymer-modified nitrocellulose spherical powders

Glycidyl azide polymer (GAP) is a promising candidate for energetic binders in future solid propellants with minimum smoke signature, reduced pollution and low sensitivity. A series of GAP-modified nitrocellulose (NC) spherical powders were prepared by an internal solution method, and its properties have been studied. SEM characterization showed that the GAP-modified NC spherical powders exhibited high roundness rate, excellent fluidity and the favorable uniformity of its corresponding propellant. XRD analyses and DSC test indicated that GAP and NC molecular chain segment had a certain degree of compatibility, and GAP molecular had desirable plasticizing effect on NC. TG–FTIR–MS coupled method revealed that GAP-modified NC spherical powders had three decomposition stages, corresponding to the decompositions of O–NO₂ groups, –N₃ groups and the main chains of NC and GAP, respectively. The onset decomposition temperature of GAP-modified NC spherical powders was 5.67 °C higher than that of pure NC spherical powders, which was very important for its safety performance. The NO₂, CO₂ and NO were detected from the gas products of first decomposition stage, while CO, H₂CO₂, CH₄, HCN and NH₃ were identified from the gas products of second decomposition stage. Finally, CO and CO₂ were produced from the third decomposition stage. The thermal decomposition process of GAP-modified NC spherical powders was presented.