Phosphorus-Silica Sol-Gel Hybrid Coatings for Flame Retardant Cotton Fabrics

This work investigates the use of organic-inorganic sol-gel coatings based on silica and phosphorous compounds for providing cotton fabrics with fl ame retardant features. To this aim, diethylphosphatoethyltriethoxysilane precursor was employed for the synthesis of several sols in combination with different chemical additives. Sols were reacted with azo-based compounds and repeatedly applied onto the cellulosic substrate in a multilayer assembly, aiming at assessing the eff ect of the concurrent presence of Si, P and N on the overall fi re behaviour of the fabric. In order to evaluate the flame retardancy of treated cellulosic fabrics, flammability tests were carried out. The obtained results showed that the phosphorus-silica coating is able to promote the formation of a stable char that acts as insulator barrier. Finally, an additive P-N effect of the ceramic oxide coating in terms of increased residue and decreased heat release rate and total burning time was observed in cone calorimetry tests.