Facile Strategy to Fabricate the Flame Retardant Polyamide 66 Fabric Modified with an Inorganic–Organic Hybrid Structure

Recently, traditional flame retardant finishing with a single metal compound has been rarely applied owing to its low effectiveness and durability. This study reports metal ion finishing in combination with surface photografting modification (M/P technology) as a novel approach to incorporate an inorganic–organic hybrid structure containing an Fe3+ ion onto the surface of the polyamide (PA) 66 fabric. Specifically, the PA fabric was first surface-modified in the presence of acrylic acid (AA) and N,N′-methylene bisacrylamide (MBAAn) during photografting pretreatment under UV irradiation (step I), then further reacted with the Fe3+ ion in the metal ion finishing (step II). After treatment with M/P technology, the fabric exhibits the required excellent flame retardancy and dripping resistance. Here, flame retardant tests show that the treated PA fabric has the highest limiting oxygen index (LOI) value of 33.4 and no melt dripping during combustion. An interesting inorganic/organic composite thermal barrier consisting of an inorganic iron oxide nanoparticle (NP) outer layer and an organic micro-intumescent inner layer can be observed on the surface of the burnt fabric. This structure could be responsible for the significant enhancement in the fire performance of the treated fabric. Importantly, the treated fabric is also highly stable during the laundering procedure, which could retain a high Fe/C ratio and an acceptable LOI value of 27.8 after washing 45 times. This confirms the achievement of durable flame retardancy after treatment with M/P technology, and its possible interaction mechanism has been discussed here.