Differential Thermal Analysis (DTA) and Thermogravimetric Analysis (TGA) Studies of Flame-Retardant Rayon Fibers

Abstract

The thermal behavior of flame-retardant fibers in which the flame-retardant chemical trapped inside the regenerated cellulose has now been studied, by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The thermograms obtained in a dynamic air atmosphere resemble those previously reported elsewhere for cellulosic materials treated with flame retardants in the conventional manner. In all cases, it has been found that the thermal degradation of the flame-retardant fibers begins at a lower temperature than for the control. A smaller quantity of flammable volatile matter is evolved and a much larger residue remains when the pyrolysis is complete. The total area of the exothermic peaks is, therefore, much smaller for the flame-retardant fibers than for the control. When the same flame-retardant fibers are heated in a nitrogen atmosphere, it can be easily seen that the onset of decomposition occurs quite suddenly at a definite temperature and clearly involves a reaction between the flame retardant and the cellulose. Examination of the flame-retardant chemicals themselves shows that these materials undergo a chemical change at approximately the same temperature, and it is this change that precipitates the interaction with the cellulose. Heating the flame-retardant rayon fibers in a conventional Fisher-Johns melting point apparatus shows that, although scorching occurs at lower temperatures than for untreated rayon, the difference is not large enough to have any effect on the processing or care of fabrics made from these fibers.