Phosphorus and nitrogen-rich oligomeric structures as durable, antibacterial and formaldehyde-free flame retardants for cotton fabrics

Abstract

Fire events, being an acute hazard, claim human lives at risk on one side and pose great damage to occupancies and properties on the other side. Textiles and furnishings are highly vulnerable to these hazards. However, such fire incidents can be mitigated by incorporating flame retardancy into textiles. This study proposes a novel flame retardant based on phosphorus and nitrogen-rich oligomeric structures obtained via condensation polymerization. The impact of phosphorus content has been investigated on the degree of flame retardancy. The structural morphology of the as-prepared flame retardants has been probed using scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Thermal responses of the prepared flame retardants and treated fabrics are characterized through thermogravimetric analysis (TGA), thermal protective performance (TPP), cone calorimeter, and differential scanning calorimetry (DSC). The treated fabrics have effectively inhibited flame propagation on fire exposure. The wash durability of the treated fabrics was found remarkable owing to the retention of high retardancy even after 30 washes. The treated fabrics exhibited a higher TPP rating by a factor of 61% due to catalyzed dehydration and the formation of a protective char layer. Furthermore, the cone calorimetry test showed a significant reduction in the HRR value by 40%, and the THR value by 27%. While LOIs of cotton textiles treated with 15% FR range from 18.2% to 37.2%. The presence of antibacterial characteristics, sustained breathability, and retention of mechanical strength of cotton fabrics adds advantages to the as-prepared flame-retardant fabrics. The current synthesis, serving as a formaldehyde-free alternative, is exceptionally well-suited for the advancement of workwear development.

Graphical abstract