A DIAGONAL COMPARISON BETWEEN THE EFFECTIVENESS OF HYDRATED MAGNESIUM SULFATE AS A FLAME-RETARDANT AND LITHIUM SULFATE AS AN INERT ADDITIVE INCORPORATED ON A CELLULOSIC FABRIC

摘要

Two hydrated sulfates, the metals of which possess diagonal resemblance in the periodic table, were considered as flame retardants. The vertical flammability test evidenced the special ability of magnesium sulfate heptahydrate (MgSO4.7H2O). The optimum add-on percent of this salt was about 10 g per 100 g cotton fabric. Despite the close diagonal resemblance between magnesium and lithium, the last-mentioned sulfate monohydrate, i.e. Li2SO4.H2O, has also been used in average ratios of 21.6-23.4% per 100 g fabric, no flame-retardancy being evidenced. Thermogravimetric analysis of both pure cotton and cotton treated with the above-mentioned salts was accomplished and their thermograms were compared and commented. The results obtained for magnesium sulfate support the "Gas Theory", expressing the expelling of water presented in the treated cellulose at a desirable range of the polymer degradation zone. Meanwhile, the application of lithium sulfate -monohydrate showed almost the same mass loss for a similar duration, which illustrated no advantage to impart flame-retardancy. Hence, the hydration water of the applied salts may play a crucial role for the capacity to impart flame-retardancy.