Fire-retardant multilayer assembled on polyester fabric from water-soluble chitosan, sodium alginate and divalent metal ion.

Lay-by-layer (LbL) assembly among water-soluble chitosan (WSC), sodium alginate (SA) and copper ion was applied to form polysaccharide-based flame retardant coating on polyester fabric. Thermogravimetric analysis (TGA) results indicated the thermal decomposition temperature of the surface-modified sample was higher than that of the original one, and increased with increasing the layers. Microscale combustion calorimetry (MCC) measurements exhibited that the heat release rate (HRR) values of the samples containing various layers were lower than that of unmodified sample and decreased as increasing layers. The peak value in HRR and total heat release of unmodified sample were 343.31 w/g and 46.11 kJ/g, while 214.29 w/g and 38.49 kJ/g for the sample containing 16-layers WSC-SA-Cu(II) respectively. The limiting oxygen index values of the samples were in the order: samples containing WSC-SA-Cu(II) layers > samples containing SA-Cu(II) layers > unmodified sample. The vertical burning reflected the sample containing WSC-SA-Cu(II) or SA-Cu(II) self-extinguished within 35 s, and the time was shorter as the sample composed of more layers. The flame retardancy of polyester fabric was significantly improved through LbL assembly of polysaccharide-based polyelectrolytes and copper ion.