Studies on the Effects of Ammonium Phosphates on the Flammability Properties of Poly(Vinyl Alcohol) Films

Abstract

Poly(vinyl alcohol) was solvent-cast from aqueous solution of n-hexane into 125 μm films. Three ammonium phosphates, (NH₄)₃PO₄, NH₄H₂PO₄ and (NH₄)₂HPO₄, were then added to produce eight sample films. Burning time, flame spread, limiting oxygen index, ignition time, and afterglow time of the samples were evaluated to determine the flame retardant efficiency of the three fillers. From the results, burning time, flame spread, after-glow time, and ignition response indices of the filled samples were found to be lower than the control sample. However, limiting oxygen index of the filled samples was found to be higher than that of the control sample. The efficiency of the fillers in fireproofing the poly(vinyl alcohol) film was found to follow the order (NH₄)₃PO₄ > NH₄H₂PO₄ > (NH₄)₂HPO₄. Additive effect was observed when the fillers are added in pairs with the fireproofing efficiency following the order (NH4)₃PO4 + NH₄H₂PO₄ > (NH4)₃PO₄ + (NH₄)₂HPO₄ > (NH₄)₂HPO₄ + NH₄H₂PO₄. Antagonism in fireproofing efficiency was observed when all the three fillers were present in the poly(vinyl alcohol) film. The fireproofing efficiency of the ammonium salts is attributed to the quantity and the ease with which ammonia (NH₃) gas is released when the filled poly(vinyl alcohol) films were heated.