LOW HIGH TEMPERATURE RELATIONSHIPS IN DINITRAMIDE SALTS BY DEA/DSC AND STUDY OF OXIDATION OF ALUMINUM POWDERS BY DSC/TG/

The dinitramide salts of ammonia (ADN), hexamethylenetetramine (HDN), potassium (KDN), and sodium (NaDN) showed a linear relationship betwee n the DSC rate of decomposition at the peak maximum and the DEA tan de lta value at the low temperature transition peak. As the cation basici ty increased in the series ADN< HDN < KDN less than or equal to NaDN, there was an increase in the tow temperature transition peak, the ener gy barrier for relaxation, and the decomposition peak temperature, and a decrease in the tans value at the low temperature transition peak, specific heat capacity, and the rate and enthalpy of decomposition. Th e more basic salts were more thermally stable (i.e., higher decomposit ion temperature) and less energetic (i.e., lower enthalpy of decomposi tion). The more internal free volume (disorder) present in these salts , the higher the rates of relaxation and decomposition. Five aluminum powders of different surface areas were analyzed by DSC in platinum sa mple pans, and it was found that the enthalpy and rate of oxidation in creased as the particle size of Al decreased while the enthalpy of the Al melt decreased. TG showed a two-step weight gain in the oxidation of Al with plateaus in the 650 and 1130 degrees C regions and the perc ent weight gain increased as the particle size of Al decreased. Variab le DSC and TG heating rate studies showed that the activation energies for the first step in the oxidation process increased as the particle size of Al increased.