Eiko Higashi

Effect of polymer addition amount and type on thermal decomposition behavior of spray-dried particles comprising ammonium nitrate, potassium nitrate, and polymer

Certain properties of ammonium nitrate (AN), such as high hygroscopicity and the thermal transformation of the crystal structure accompanied by volume changes, pose problems for industrial applications of AN. To solve these problems, we previously prepared AN-based particles by spray-drying. The particles contained potassium nitrate (PN) as a phase stabilizer and a polymer (e.g., PVA, CMCs, and Latex) to produce a moisture-resistant material. Herein, we investigate the thermal decomposition of spray-dried AN/PN/polymer particles by differential scanning calorimetry and Thermogravimetry–Differential thermal analysis. Comparison of the thermal decomposition of AN/PN/polymer materials with different amounts and types of polymers suggested that thermal decomposition at lower temperatures resulted from the reaction of AN with the molten polymer or decomposition products derived from the polymer. Therefore, it can be concluded that the thermal stability of the AN/PN/polymer was exclusively determined by the thermal properties of the polymer components.

Spontaneous Ignition Behavior of Nitrocellulose–Sulfuric Acid Mixtures

Nitrocellulose (NC) is known to undergo spontaneous ignition, and its thermal stability has been previously reported to decrease in the presence of sulfuric acid. In this study, we evaluated the decomposition and ignition behavior of NC in the presence of sulfuric acid using an accelerating rate calorimeter (ARC) and hand-built ignition testing equipment. The results of the ARC experiment indicated that the thermal stability of NC decreased when the amount of sulfuric acid was increased above 10-5 mol/g (NC). In addition, when NC (4 g) mixed with sulfuric acid (6.6 mol/L, 1 g) was isothermally stored at 75°C in a glass flask, the color of the reaction mixture changed from white to brown. After 83–127 min, NC spontaneously ignited and produced a loud explosion.