Effect of hybrid phosphorus-doped silica thin films produced by sol-gel method on the thermal behavior of cotton fabrics

The aim of this work was to prepare hybrid organic-inorganic silica thin films to provide cotton fabrics with flame retardant properties and to investigate the films' influence on the thermal and burning behavior of the treated samples. The fabrics were modified with three different sols in order to study the effect of pure silica sol-gel precursor, γ-aminopropyltriethoxysilane (APTES), and that of the hybrid sols consisting of the APTES and the phosphorus compound diethylphosphite. Furthermore, in order to improve the cross-linking degree and the phosphorus-nitrogen synergistic effect on flame retardancy of the P-doped silica thin film the melamine-based resin was added in the third sol. To evaluate the chemical structure of the coating material, pure xerogels of the treatment solutions were applied to glass slides and tested by ATR FT-IR spectroscopy. The cotton fabrics were impregnated with the sols by a padding-squeezing process and then dried. Thermal behavior of the treated cotton samples was investigated by thermogravimetric/differential scanning calorimetry analysis (TGA-DTG/DSC) and compared to the untreated one. The flame retardancy was tested according to the ASTM D 1230 standard method. The results showed a substantial enhancement of char-forming properties and flame retardancy for the fabrics modified with the thin films.