Novel cellulosic okra woven fabrics with enhanced flame retardant properties via synergistic coating of boric acid and ammonium polyphosphate

Lignocellulosic fibers show combustibility, so it’s unsafe to use these fibers as reinforcement in flame retardant biocomposites that are designed for automotive textiles. Therefore, enhancing its flame retardancy is essential. This study aims to enhance the flame retardant characteristics of okra woven fabric (OWF) by using a synergistic coating of boric acid (BA) and ammonium polyphosphate (APP). Flame retardancy was evaluated through the analysis of limiting oxygen index, cone calorimeter, and vertical combustion test. An exploration of various concentrations of BA+APP was used, revealing that the coating of OWF with a composition of 6% BA+6% APP (wt%) exhibited the highest flame retardancy. TGA and DSC were employed to investigate the thermal degradation, which revealed that 6% BA+6% APP coated OWF yields the maximum char residue of 53% at 695 °C temperature. The alterations in chemical structure resulting from the BA+APP coating were analyzed using FTIR, XPS, and EDX, while SEM examined the deposition of the coating layer. The results of tensile properties indicated that BA+APP coating lead to a notable reduction in both tensile strength and elongation at break, as corroborated by ANOVA statistical analysis.