Investigation on activation energy of ground spinner pyrotechnic mixture by altering grades of aluminium (Alxxx) and proportions of dextrin(C6H10O5)n

The combustion process of pyrotechnic mixtures is to be designed in a precise manner since it is governed by activation energy, entropy, enthalpy and Gibbs free energy of chemical reaction. The traditional ground spinner pyrotechnic mixture consists ofAlxxx(Aluminium grades) as fuel, Ba(NO₃)₂(Barium Nitrate) and KNO₃(Potassium Nitrate) as oxidisers and (C₆H₁₀O₅)_n (Dextrin) as binder cum secondary fuel. This study investigates on the energy changes occurring in the pyrotechnic composition by changing primary fuel grades and altering the binder cum secondary fuel composition. It was observed from the burn rate test that, as the particle size of aluminium decreases, the burn rate increases. Further, the activation energy, onset temperature and impact energy are determined by thermogravimetric analysis and Bundesanstalt für Material forschung und-prüfung (BAM) testers. The outcomes indicate that an increase in dextrin leads to a rise in both the onset temperature and impact energy. It was also observed from the studies carried out using NASA‘s computer program Chemical Equilibria Applications (CEA) that with increase in the percentage of dextrin, the entropy increases, but enthalpy and Gibbs free energy decrease. The findings also disclose that the sample containing Al_xxx–43% and (C₆H₁₀O₅)_n–10% exhibits 20.5% increase in the burn rate, 22.16% increase in enthalpy and 23.35% increase in Gibbs free energy.