Durable flame-retardant behavior of cotton textile with a water-based ammonium vinyl phosphonate

A novel coating system for fabricating durable flame-retardant cotton textiles was invented based on halogen-free water-based ammonium vinyl phosphonate (AMVP) via a dip-dry-cure process. The flame retardant was not only reacted with cellulose through P-O-C covalent bond but also prevented the acid brittleness of cotton fibers. The prepared fabrics have shown excellent flame retardance, good hand feel, and durability. The limiting oxygen index (LOI) value of the AMVP treated cotton fabric with the weight gain value of 13.6% was 36.7% while the LOI value of the fabric still has remained 27.3% after 50 washing cycles. It can still be self-extinguished without any lateral flame spread. The cone calorimetry results showed that the peak heat release rate (PHRR) and the total heat release (THR) of AMVP treated cotton were 87.36% and 48.94%, respectively, lower than that of control cotton. All results of thermal degradation behavior, pyrolysis products, the morphology, and chemical components of the charred residue revealed that AMVP coating altered the thermal decomposition pathway of the treated cotton. It induced the formation of a stable char layer rather than flammable gases, which results in the excellent physical barrier retarding the heat flux and flame. Furthermore, the whiteness and softness of the AMVP treated cotton were sustained well, although the tensile strength and breaking elongation of cotton fabrics had a slight decrease. © 2021 Elsevier Ltd