Chitosan: A new route for increasing the efficiency of stannate/phosphate flame retardants on cotton

Sodium stannatc/phosphate is an ideal eco-friendly flame retardant agent for cotton fabric. Development of this technique is an essential way to overcome some of its disadvantages such as the harsh feeling as a result of using high concentration of sodium stannate. Chitosan is added in the phosphorylation bath as a nitrogen source and to facilitate the phosphorylation process. Incorporation of 1% chitosan could decrease the sodium stannate concentration to the one-third of the amount that IS used in the conventional method. Increasing the stannate concentration in the finishing bath from 10 to 30% could enhance the flame retardancy of the cotton fabric. Thermogravimetric analysis of the treated cotton fabric shows an increase in the residual percent of the fabric and decrease in both thermal degradation onset point (TDOP) and maximum degradation rate point as a function of stannate concentration. Increasing diammonium hydrogen phosphate (DAHP) from 2 to 10% in the finishing bath shows an increase in the residue at 500 degrees C to 39.24%. Phosphorus and nitrogen percentages show an increase in their values till reaches to 1.39 and 1.72, respectively. The effect of curing temperature and time, chitosan concentration, and the sequence of treatment are studied in detail.