Synergistic Effect of Sodium Polymetaphosphate-Urea on the Flame-Retardancy Imparted to a Polyester Fabric

The synergistic effect between sodium polymetaphosphate (Calgon) and urea on the flame-retardancy of a polyester fabric (plain construction weighing 160 g/m2) is described in this study. The laundered bone-dried weighed specimens were impregnated with suitable concentrations of individual aqueous sodium polymetaphosphate (Calgon) or urea solutions and some sets were impregnated with appropriate admixed solutions of both chemicals. A vertical flammability test was then carried out. An acceptable synergistic effect was obtained using an admixed bath containing 0.4 molar sodium polymetaphosphate and 4.0 molar urea solutions for imparting flame-retardancy to a polyester fabric. The optimum weight of the mixture needed to impart flame-retardancy was about 36.52 g anhydrous additives per 100 g fabric. The results obtained are in favour of “phosphorus-nitrogen synergism” required to retard the flame. They comply with “chemical theory,” “gas theory,” and “condensed phase retardation.”