Durable and Environmentally Friendly Flame-Retardant Finish on Wool via Graft Copolymerization of Vinyl Phosphonic Acid

A durable and environmentally friendly flame-retardant treatment process on wool via graft co-polymerization of vinyl phosphonic acid (VPA) was investigated. The influence of temperature, time, VPA, and catalyst on the grafting yield (GY) was studied. Employing response surface methodology, the grafting parameters were optimized, and the highest GY was achieved. Thermogravimetric studies showed a 3.86% increase in the remaining char ratio at 750°C for the wool fabric after graft co-polymerization of VPA. Flame retardancy of wool fabrics was evaluated with respect to their limiting oxygen indices (LOI) and the ease of ignition measurements. The sample with 8.1% GY exhibited a 35.89% increase in LOI and over a 3.66-fold increase in ignition time. The chemical structure of the grafted wool is proposed according to FTIR and 31P Solid-state MAS NMR evidence. The presented flame-retardant finish process was deemed to be a green and durable substitute for the conventional, semi-durable, and non-environmentally friendly processes.