Organophosphorus/Cotton Nanocomposite Knitwear for Flame Protection; A Microscopic Evaluation Approach

Chemically modified nanocomposite fibers are an area of increasing interest in protective clothing. Such nanocomposites create a protective layer on the fiber surface, preventing flame spread. The nature of the fiber material and fabric construction is crucial in determining overall performance. Significant work has been carried out focusing on different materials for flame-retardant finishing; however, the area of fabric structure modification has not been addressed. In this investigation, structures of rib and interlock have been developed using cotton-Spandex yarns co-knitting. Nanocomposite cotton fabrics with an organophosphorus (N-methoxymethyl melamine) flame-retardant finish have been engineered. Vertical flammability tests revealed the significance of knitted structure modification in tailoring flame retardancy, with less char length through tuck and miss-bourlette. Microscopic evaluation revealed unique burning behaviors for each distinct pattern, and the fiber-level burning variations were identified through SEM analysis. Spandex incorporation enhanced flame retardancy, while the thermal resistance was decreased. Thermo-physiological comfort characterization before and after the flame finishing process showed noticeable changes owing to surface morphology and chemical modification after nanocomposite formation. A decrease in air permeability was observed, and the OMMC index was enhanced after finishing.