Enhancement of Fire Resistance in Cotton/Polyester and Cotton/Linen Blends Using Sol-Gel Derived Silicate/Phosphate Coatings

This study presents an innovative sol-gel flame-retardant system utilizing sodium silicate, urea, and sodium hy-drogen phosphate for cotton/polyester (60/40) and cotton/linen (70/30) blends. This formulation uses cheap, water-soluble precursors and fixes at ≤75 °C without needing a high-temperature curing phase, which is different from traditional phytic acid- or nanoparticle-based sol-gel coatings. The combined effects of P, N, and Si generated a solid protective layer that cut the time it took for materials to smolder from 60 seconds to 3–4 seconds in cotton/polyester and 25–28 seconds in cotton/linen. It also cut the length of the char from 220 mm to about 25 mm with less than 5% loss of tensile strength. SEM/EDX confirmed that silicon and phosphorus were evenly deposited on the fiber surface. The technique is easy, can be utilized on a large scale, and is good for the environment. It is a good alternative to current sol–gel flame-retardant technologies for blended textiles used in protective, household, and industrial settings.