Flame retardant polyacrylonitrile fabrics prepared by organic-inorganic hybrid silica coating via sol-gel technique

The aim of this paper was to explore a novel technique to impart polyacrylonitrile (PAN) fabric flame retardancy. The fire retardant sol was firstly prepared by adding phytic acid and urea as phosphorus-nitrogen synergistic agent to tetraethoxysilane (TEOS). The resulting sol was then coated on PAN fabric and gelated to produce fire retardant PAN fabric. The structure, components, thermal properties and combustion performance of the resultant fabrics were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG), differential scanning calorimetry (DSC) analysis, limited oxygen index (LOI) test, and microscale combustion calorimeter (MCC). The results showed that the coated PAN fabrics possessed an excellent thermal stability and flame retardancy. Compared with the control sample, the fabric coated with phosphorus-doped silica coating (Si-P) was self-extinguishing when the fire source was removed. Furthermore, the fabric coated with phosphorus and nitrogen-doped silica coating (Si-P-N) was incombustible with the highest LOI value of 42.1%, displaying excellent fire retardancy.