Synthesis of a novel phosphorus-nitrogen reactive flame retardant and its application on cotton fabric

Abstract

Abstract A novel halogen-free, formaldehyde-free, phosphorus-nitrogen-based flame retardant (FR), ammonium salt of erythritol phosphoric ester acid (AEPEA), was synthesized and coated onto cotton fabrics to increase the flame resistance of cotton. The structure of AEPEA was characterized by hydrogen nuclear magnetic resonance (1H NMR). Fourier-transform infrared(FTIR) and X-ray photoelectric spectrometer (XPS) results proved that AEPEA was chemical grafted on the cotton through P-O-C bond. The limiting oxygen index (LOI) of cotton treated with 300 g/L AEPEA reached 40.1% and the carbon length was 4.2 cm. After 50 laundering cycles (LCs), the LOI value could still reach 27.8%. Thermo-gravimetric (TG) and cone calorimetry test (CCT) were used to further investigate the flame retardancy and thermal stability of cotton fabric, and the results proved that the thermal stability of treated cotton was greatly improved. Scanning electron microscopy (SEM) showed that there was no significant change on the surface of treated cotton. The results of X-ray diffraction (XRD) showed that the crystalline morphology of cotton fabric was almost unchanged after flame-retardant finishing. Besides, the mechanical properties of the treated cotton only decreased slightly.