Phosphorous containing poly(amidoamine-organosilicon) (P@PAMAMOSi) flame retardants: Synthesis and sol-gel application on cotton fabrics

A novel hyperbranched phosphorous containing poly(amidoamine-organosilicon) (P@PAMAMOSi) was successfully synthesized and the structure was characterized by fourier transform infrared spectra (FT-IR) and NMR. The cotton fabrics were wrapped with P@PAMAMOSi by sol-gel method. The P@PAMAMOSi modified cotton fabrics were proven by FT-IR and scanning electron microscopy (SEM). The thermal stability and combustion properties of the blank cotton and treated cotton fabrics were explored by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical flammability, and cone calorimetry. The data of TGA indicated that modified cotton fabrics have exquisite thermal stability, when the temperature reached 700 °C, the char residues of A₃₀ treated cotton, B₃₀ treated cotton, and C₃₀ treated cotton were 29.5, 34.5, and 28.8 %, respectively; which is better than the 12.7 % of blank cotton. The results were verified by the LOI and combustion tests of cotton fabrics. The flame-retardant mechanism of treated cotton fabrics was analyzed by the FT-IR, X-ray photoelectron spectrometry (XPS), SEM, and energy dispersive X-ray spectroscopy (EDS), the treated cotton fabrics showed condensation phase and gas phase flame retardant mechanism. In addition, treated cotton fabrics showed desirable physical properties and mechanical properties.