Eco-friendly flame-retardant coatings based on γ-ureidopropyltriethoxysilane for cotton fabrics with improved flame retardancy and mechanical properties

In this study, a bio-based coating was constructed by sol-gel technique deposition based on γ-ureidopropyltriethoxysilane (TESPR) and ammonia phytate (AP) to acquire fire-safety cotton fabrics. The flame retardancy, thermal stability, burning behavior, flame retardant mechanism, and mechanical properties of the coated cotton fabrics were evaluated. With about 9.91% weight gain of TESPR/AP coatings, the coated cotton fabrics self-extinguished in the vertical flame test, and the limiting oxygen index arrived at 31%. The thermogravimetric analysis revealed that although the initial thermal degradation temperature of Cotton/TESPR/AP was lower than that of uncoated cotton fabrics, the char residues in the high-temperature range increased. Meanwhile, the results of the cone calorimetry test revealed that both the heat and smoke production released of cotton/TESPR/AP was greatly reduced during burning. The flame-retardant mechanism of this system was eventually suggested depending on the assessment of gaseous products and char residues. Furthermore, TESPR/AP coatings did improve the breaking force of cotton fabrics compared with that of AP coatings, while retained better air permeability compared with that of uncoated cotton fabrics. These bio-based coatings not only ensure safety, but also provide a practical flame-retardant solution for inflammable natural fabrics.