Thermal analysis of pyrotechnic compositions containing potassium chlorate and lactose

Abstract

Thermal analysis of a mixture containing potassium chlorate and lactose 50:50, which is commonly used in vaporizing pyrotechnic compositions, has revealed that there are two principal exothermic reactions in the absence of air. The first, coinciding with the fusion of lactose at approximately 200°C, is the oxidation of the lactose by the chlorate and may be represented by the stoichiometric reaction (1). 8 KC10 3+ C 12 H 22 O 11− H 2O→8 KC1+12 CO 3+12 H 2O , It is postulated that this reaction is initiated by the partial solution of the potassium chlorate in the lactose, and terminates when there is no liquid lactose in the mixture. This is followed immediately by the dehydration of lactose, represented by Eq. (2) C 12 H 22 O 11− H 2O→12 C+12 H 2O . This reaction terminates when approximately half the maximum possible amount of water is evolved, and does not contribute to the exothermicity at this stage. The second exothermic reaction occurs at about 340°C and is probably initiated by the fusion of the potassium chlorate. This reaction is the oxidation of the carbonaceous organic residues by the remaining potassium chlorate. Since there is an excess of fuel in this mixture other slow exothermic reactions occur in the presence of air due to further oxidation of the fuel. These reactions will not occur during combustion, when the ingress of air is prevented. An application of thermal analysis to a practical pyrotechnic composition is presented and discussed.