Thermal stability and flammability of cotton fabric with TiO2 coatings based on biomineralization

Abstract

Cotton fabric has a wide application in the textile and furniture industries. However, because of its chemical composition and physical structure, it is highly flammable, which seriously threatens life and property. Incorporating insulating inorganic coatings onto cotton fabrics to mimic the formation of char layer, is a relatively new and effective strategy to improve their flame retardancy. In this study, as an affordable, environmentally friendly, and energy-efficient approach, biomineralization was applied to produce TiO2 coatings on the surface of cotton fabric to form a flame retardant system. The surface morphology and chemical compositions were well characterized first, and the flammability of treated cotton fabric was comprehensively evaluated using different techniques from micro to macro-scale. TiO2 coated cotton shows better flame resistance at the molecular level. The TiO2 coating produced by biomineralization exhibits a strong effect to reduce the burning intensity of cotton. The peak heat release rate is reduced by 5.5%, 27.1%, and 32.6%, respectively for TiO2 coated cotton with 1 cycle, 3 cycles, and 7 cycles of treatment. It also shows the potential to slow down the fire spread rate and the propensity of fire development. The protective effectiveness depends on the number of cycles of treatment. With only 1 cycle of treatment, it is not enough to attain a uniform TiO2 protective coating and thus it shows limited flame retardant performance. Once a uniform TiO2 coating is formed by biomineralization, it shows strong flame retardancy. With 7-cycle treatment, its limiting oxygen index can even reach 21.0%.