Flame retardancy of cotton textiles by plasma-induced graft-polymerization (PIGP)

The permanent fire proofing of textiles of natural origin such as cotton is still challenging because only a surface treatment can be applied. Moreover, to be resistant to washing or harsh weather conditions the flame retardant must be fixed strongly to the surface, most efficiently achieved via covalent bonds. For that purpose, the simultaneous grafting and polymerization of fire retardant monomers on cotton fabric induced by argon plasma have been investigated with four acrylate monomers containing phosphorus, diethyl(acryloyloxyethyl)phosphate (DEAEP), diethyl-2-(methacryloyloxyethyl)phosphate (DEMEP), diethyl(acryloyloxymethyl)phosphonate (DEAMP) and dimethyl(acryloyloxymethyl)phosphonate (DMAMP), which are known to be effective for this application. We also report the synthesis and the plasma-induced graft-polymerization (PIGP) of two new phosphoramidate monomers, diethyl(acryloyloxyethyl)phosphoramidate (DEAEPN) and acryloyloxy-1,3-bis(diethylphosphoramidate)propan (BisDEAEPN) on cotton fabrics. Their flame retardant effect was compared with the previously used acrylate phosphate and phosphonate monomers. DEAEPN and BisDEAEPN exhibit the highest LOI values (28.5 and 29.5 respectively). The good flame retardant properties of these phosphoramidate monomers are attributed to the presence of nitrogen which causes a synergistic enhancement in the efficiency of phosphorus-based flame retardants. The grafting and the polymerization processes taking place on the surface of the cotton textile were followed by weighing measurements, IR (ATR) spectroscopy and SEM. The fire retardant character of the treated fabrics was investigated by thermogravimetric analyses and LOI measurements. The durability of the treatment was investigated by using the accelerated method of laundering proposed by McSherry et al.