Multifunctional Meta-Aramid Fabrics Enhanced with Inherent Flame-Retardant Polyurea Coatings: Integration of Mechanical Strength, Puncture Resistance, and Self-Healing Properties

In this study, a solvent-free, slow-curing, inherently flame-retardant polyurea coating was successfully developed through an optimized formulation. The novel polyurea was synthesized using mixed Schiff base latent curing agents derived from terminal polyether amines with different-number average molecular weights (D2000 and D400), methyl isobutyl ketone, and polyethyl phosphate glycol ester (OP550). Subsequently, polyurea/meta-aramid (PUA/AF) composite fabrics were fabricated via a scraping coating technique. Thermogravimetric analysis revealed enhanced char formation and reduced decomposition temperatures due to the incorporation of OP550. Comprehensive flame retardant performance was demonstrated through vertical flame testing, limiting oxygen index, and micro-scale combustion calorimetry, with results showing significantly reduced heat release rates, lower total heat release, and increased residual char. Mechanical evaluations indicated marked improvements in tearing, tensile, single-yarn tensile, and bursting forces, attributed to strong fiber-polyurea interfacial interactions, as confirmed by detailed SEM morphological analyses. Moreover, the PUA/AF composites exhibited excellent static puncture resistance and effective self-healing capability. Collectively, these advancements highlight the potential of PUA/AF composite fabrics as promising candidates for advanced protective textiles, integrating superior flame retardancy, mechanical strength, puncture resistance, and self-repairing functionality.