Synthesis and characterization of a novel phosphorus–nitrogen‐containing flame retardant and its application for textile

Abstract

The economic and environmentally friendly flame‐retardant compound, tetramethyl (6‐chloro‐1,3,5‐triazine‐2,4‐diyl)bis(oxy)bis(methylene) diphosphonate (CN‐1), was synthesized by a simple two‐step procedure from dimethyl phosphate, and its chemical structure was characterized by 1H, 13C, and 31P nuclear magnetic resonance and gas chromatography mass spectroscopy. Using the traditional pad–dry–cure method, we obtained several different add‐ons (wt%) by treating cotton twill fabric with flame retardant (CN‐1). Thermogravimetric analysis, in an air and nitrogen atmosphere, of the modified cotton showed that decomposition occurred ~230°C with 16% residue weight char yield at 600°C, indicating high thermal stability for all treated levels. Limiting oxygen index (LOI) and the vertical flammability test were employed to determine the effectiveness of the flame‐retardant treatments on the fabrics. LOI values increased from ~18 vol% oxygen in nitrogen for untreated fabric to maximum of 34 vol% for the highest treatment level. Fabrics with higher levels of flame retardant also easily passed the vertical flammability test. Furthermore, Fourier transform infrared and scanning electron microscopy were utilized to characterize the chemical structure as well as the surface morphology of the flame‐retardant treated twill fabrics, including char area and the edge between unburned fabric and char area. Copyright © 2011 John Wiley & Sons, Ltd.