Thermal behavior and stability of HNIW (CL20)

The thermal stability, phase behavior, and decompn. of the explosive .epsilon.-2,4,6,8,10,12-hexanitrohexaazaisowurtzitane (HNIW) were studied. At >164.degree. irreversible transition to the .gamma.-polymorph was obsd. which is accompanied by an increase of vol. Differential scanning calorimetry and differential thermogravimetry indicate a 2-step decompn. at >210.degree.. The evolution of gaseous decompn. products was monitored by rapid scan FTIR spectroscopy. The main products are CO2, NO2, N2O, and HCN. In addn., a solid residue remains whose IR spectrum is given. A mass loss due to decompn. was also obsd. below 210.degree.. Kinetic calcns. show this low-temp. decompn. reaction to be of 1st order and autocatalytic.