Banana pseudostem sap and boric acid— A new green intumescent for making self- extinguishing cotton fabric

Abstract

The flame retardant functionality has been imparted in cellulosic fabric using mixed formulation of banana pseudostem sap (BPS) and boric acid (BA). The extracted sap is mixed with different concentration of BA and applied onto the. pre-mordanted bleached and mercerized cotton fabrics at elevated temperature. It is found that BA acts as a strong afterglow and smoke arresting agent, when applied at the concentration of > 2% (w/v). Flame retardant characteristics of both the control and the treated fabrics have been analysed in terms of limiting oxygen index, vertical flammability and temperature generation profile during burning. The (BPS+3% BA) treated cotton fabric sample shows the LOI value of 42 and the specific char length of 14cm after vertical flammability test. The thermal degradation and pyrolysis mechanism are also studied, using both thermogravimetric analysis and fourier transform infrared spectroscopy. Besides, the charring morphology and mechanism of both the control and the treated fabric is analysed in detail by scanning electron microscopy and FTIR analysis. A char structure model and the mechanism of char formation have also been proposed in the paper.