Flame Retardant Effects of Fabrics Finished by Hybrid Nano-Micro Silica-based Sols

An efficient, transparent, convenient sol-gel process was attempted to produce hybrid sols including flame retardant and finish cotton fabrics. Using TEOS (Tetraethyl Orthosilicate) as a precursor and gelatin as a flame retardant additive, a series of hybrid silica sols were prepared and then coated on a cotton fabric. KH550 was used as cross-linking agent for the sake of strong linkage formation between the hybrid silica sol and cotton fabric. Limiting Oxygen Index (LOI), Thermogravimetric Analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) experiments were conducted to determine flame retardancy, characterize pyrolysis properties and identify microstructural functional groups on the surfaces of sols-finished fabrics. Results show that finished cotton fabrics have improved flame retardancy, especially the samples treated with KH550-SiO2-gelatin hybrid sol processes higher LOI (23.0-24.5 %) than original fabric; after treatment cotton fabrics show widened pyrolysis range of temperature and the fabric finished by KH550-SiO2-gelatin hybrid sol shows maximum range of 293.5-564.5 ℃. Besides, the residual char ratio is also increased. In the FTIR experiment, it is found that the stretching vibration of the -CHO at 1700 cm-1 from cotton fabric is greatly attenuated in the presence of KH550-SiO2-gelatin. Also a strong absorption peak appears at 1030 cm-1 due to stretching vibration of C-N from gelatin, indicating that the KH550-SiO2-gelatin particles have been successfully attached to the cotton fabric. Generally, the flame retardant effects induced by sols are ranked as follows: KH550-SiO2-gelatin> SiO2-gelatin> SiO2-KH550> SiO2.