Effect of metal salicylates on the ignition and combustion of polystyrene

Abstract

The effect of transition metal salicylates of Co, Ni, Mn and Fe on the ignition and combustion of polystyrene has been studied. Co and Ni salicylates have four molecules of H₂O as water of crystallization whereas Mn and Fe salicylates have only two H₂O molecules coordinated to the metal ion. Except Fe which exists in 3+ oxidation state, all other salicylates exist in 2+ state. Thermal studies show that the salicylates exist in 2+ state. Thermal studies show that the salicylates undergo a three step decomposition. In the first step loss of the H₂O molecules takes place, in the second step removal of one salicylate occurs and in the third step oxidation of the residue from the second step leads to the formation of oxides. In Fe salicylate, however, the two salicylates are removed in a single step. The case of ignition of polystyrene in the presence of salicylates is explained on the basis of the increase in the rate of its gasification prior to ignition. The sensitization in combustion has been explained by considering the increase in the surface temperature in presence of salicylates, this increase is due to the exothermic decomposition of salicylates on the surface.