Hybrid eco-friendly coating on bamboo fabric through Taguchi formulations for flame and thermal resistance

The flammability of natural fibers is their main limitation in high-temperature engineering applications, a contemporary issue in the present green engineering sector. Therefore, the current investigation focused on developing fire-resistant natural fibers through surface coating with hybrid biochemicals using the Taguchi approach (L9 orthogonal array). The low-cost and eco-friendly chemicals, chitosan (CTS), sodium bicarbonate (SBC), and ammonium polyphosphate (APP), were utilized by dissolving 3 wt% and 6 wt% of each in an aqueous medium and coating the mixture on bamboo nonwoven fibers (BNFs). The surface chemistry of the coated BNFs were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The effect of the hybrid coating on the flammability and thermal stability of the BNFs were studied. The experimental results indicate that the synergistic effect of the chemicals through the intumescent mechanism and metal bicarbonate effectively improved the flame resistance of BNFs. The results of the vertical burning test of the coated fibers indicated their exceptional self-flame-extinguishment, reaching the V0 level, with excellent thermal stability and almost 40 wt% residue at 700 °C. Overall, the hybrid coat could enhance the flame-resistant properties of natural fibers, thereby overcoming the limitations of natural fibers and making them suitable for use as sub-structural components in engineering applications as reinforcements.