Flame resistance behavior of cotton fabrics coated with bilayer assemblies of ammonium polyphosphate and casein

This research report discusses the intumescent flame resistance and physiological comfort of cotton fabrics after being coated with bilayer assemblies of different concentrations of ammonium polyphosphate (APP) and casein solutions. The flame resistance was investigated using horizontal flame propagation, cone calorimetry and thermo-gravimetric analysis, whereas physiological comfort was estimated in terms of air permeability, water vapor permeability and stiffness testing. From cone calorimetry results, the coated fabrics showed very slow combustion kinetics as the concentration of casein or APP was increased. Although, higher concentration of casein was found to produce higher char residue, but the physiological comfort properties were deteriorated beyond 5 wt% casein. The images of burnt samples confirmed the formation of a distinct intumescence layer of char residue and it was also validated from the measurements of thermal conductivity of char residues. In this way, the presented work showed that the casein could perform number of functions such as catalyzed dehydration, accelerated charring and intumescent char formation in APP based intumescent systems.