Correlation between Limiting Oxygen Index and Phosphorus Content of the Cotton Fabric Treated with a Hydroxy-Functional Organophosphorus Flame Retarding Finish and Melamine–Formaldehyde

The combination of a hydroxy-functional organophosphorus flame retardant agent (FR) and melamine–formaldehyde (M–F) was used as a durable flame retardant finishing system for cotton fabrics. M–F functions as a binder between FR and cotton cellulose, thus making this flame retardant system durable to home laundering. M–F also provides nitrogen to this system, therefore enhances its flame retarding performance by means of phosphorus–nitrogen (P–N) synergism. Limiting oxygen index (LOI) is one of the most commonly used parameters to indicate the flammability of textiles as well as other materials. In this research, we investigated the correlation between LOI and the phosphorus content on the cotton fabric treated with the durable flame retarding system described above. Phosphorus concentration on the fabric was analyzed by inductively coupled plasma atomic emission spectroscopy (ICPAES). We developed a statistical model to predict the LOI of the treated cotton fabric based on the phosphorus concentration and the concentrations of the M–F in the finish solutions.