On the flameproof treatment of ramie fabrics using a spray-assisted layer-by-layer technique

Flame-retardant coatings were applied to ramie fabric. These consisted of oppositely-charged polyelectrolyte polyethyleneimine (PEI) and ammonium polyphosphate (APP). Application was made using, both a spray-assisted layer-by-layer (LBL) technique and by the conventional dipping LBL method. Thermogravimetric analysis showed that all the coated fabrics left two to three times as much residual char as did uncoated ones. Use of the spraying method was able to achieve the similar thermal stabilization at fewer bilayer number in coating that compared with the dipping method. Additionally, spraying also exhibited a more obvious reduction in both heat release capacity and peak heat release rate in a microscale combustion calorimeter test and cone calorimetry. The cloth acquired the same self-extinguishing property during the vertical flame test and resulted in a more compact and intact char residues. These results demonstrate that the spray-assisted LBL technique represents a relatively efficient and practical alternative to the conventional dipping LBL technique for imparting flame-retardant behavior to ramie fabric.