Flame Retardant Finish of Silk Fabric with Dimethyl Phosphonate Doped Silica Sol

In this paper, a dimethyl phosphonate doped (P-doped) silica sol was prepared from a tetraethyl silicate inorganic precursor and applied to silk fabric as a flame retardant finish through the sol-gel process. The X-ray photoelectron spectroscopy (XPS) analysis and scanning electron microscope (SEM) images indicated a phosphorus-containing silica network successfully formed on the silk fabric surface. The flammability of the treated silk fabric was investigated by the limiting oxygen index (LOI) and vertical combustion test. The results indicated that the treated silk fabric were flame retardant with a higher limiting oxygen index (LOI) and shorter damage length. Moreover, micro calorimeter combustion testing and thermal gravimetric analysis indicate 50% of P-doped silica sol treated silk fabric exhibited a lower heat release rate and higher char residue, which demonstrates a synergistic effect between the silica and phosphorus.