High-performance polyester composites using electroless Ni-P coated Kevlar fibers and nano-TiO ₂ : a study on mechanical behaviour

Abstract This study presents an integrated approach to improving the mechanical performance of polyester-based composites through electroless nickel–phosphorus (Ni-P) coated Kevlar fibers combined with nano titanium dioxide (TiO 2 ) additives. Conventional Kevlar-reinforced polymers often exhibit limited stress transfer due to weak fiber–matrix adhesion. To address this issue, Kevlar fibers were alkali-treated using sodium hydroxide to enhance surface roughness and chemical reactivity, followed by electroless Ni-P coating to achieve uniform metallization and superior interfacial bonding. In parallel, TiO 2 nanoparticles were dispersed within the polyester matrix to increase stiffness, restrict chain mobility, and support nanoscale crack-arresting mechanisms. Hybrid composites were fabricated with controlled variations in fiber and nanoparticle content, and their mechanical properties were examined through tensile, flexural, compressive, impact, and hardness tests. The results indicate that Ni-P coated fibers significantly enhance tensile strength, flexural rigidity, and impact resistance compared with uncoated fibers. TiO 2 addition further contributes to improved stiffness and toughness by promoting uniform stress distribution. A reduction in water absorption was observed in coated samples without compromising structural integrity. Morphological analysis confirms improved fiber–matrix adhesion and reduced interfacial defects. Overall, the synergistic effects of surface metallization and nano reinforcement demonstrate strong potential for high-performance composite applications in automotive, transportation, and protective structures.