The thermal decomposition mechanism of nitrocellulose aerogel

Nitrocellulose (NC) aerogel was prepared by sol-gel synthetic approach and supercritical carbon dioxide drying method as a new energetic matrix for nano-composite energetic materials. Scanning electron microscopy of the NC aerogel reveals that the aerogel is accumulated by nanoparticles with a diameter of 30-50 nm and has nano-porous structure, which makes the thermal behavior of the NC aerogel different from that of the NC fibers. Therefore, the thermal properties of NC aerogel were determined by TG/DSC, which showed that the maximum decomposition temperature and the exothermic peak temperature of NC aerogel decreased 8.2 and 11.4°C than NC fibers, respectively. By TG/FTIR technology combined FTIR test of the condensed phase, the decomposition mechanism was derived based on the experimental results. The initial reaction of NC aerogel decomposition is the splitting of urethane bond, and then, the scission of -O-NO₂ bonds happens. Moreover, the macromolecular chains' scission site of NC aerogel firstly occurs at -C-O-C- in the ring, while the chains of NC fibers break at -C-O-C- between the rings.