Development of fire retardant sisal yarn

For the first time flame retardant functionality was imparted in sisal (leaf fibre) yarn using N-methylol dimethylphosphonopropionamide (MDPA) based formulation. MDPA formulations were applied to sisal yarn in various concentrations by the dipping method followed by drying and curing. The formulation was optimized on the basis of tensile strength of the treated yarns. Flame retardancy of the treated yarn was evaluated by limiting oxygen index (LOI) and vertical burning behavior testing with measurement of the char length. The LOI value of the treated sisal yarn was found to increase by 1.5 times after an application of 450 gpl MDPA formulation. Thermo-gravimetry and char morphology analysis of the control and the treated sisal yarn were analysed to understand the fire retardancy mechanism of treated sisal yarn. Further, washing durability of the treatment was also evaluated.