Durable flame retardant finishing of cotton fabrics with organosilicon functionalized cyclotriphosphazene

The organosilicon functionalized cyclotriphosphazene (N3P3[NH(CH2)3Si(OC2H5)3]6) was synthesized and characterized by nuclear magnetic resonance (NMR) and Fourier transform infrared spectra (FTIR), then it was applied to cotton fabrics through a convenient pad-dry-cure process to fabricate flame retardant coating with different add-on values. The coating on cotton fabrics was confirmed by the scanning electron microscopy (SEM). Excellent flame retardancy was found from limited oxygen index (LOI) and vertical burning test. The coating induced an earlier decomposition of cellulose, enhanced the formation of the stable char and significantly reduced the heat release rate. Moreover, flame retardancy of the coated fabrics did not change significantly after 30 soaping cycles.