Enhancing the Mechanical Performance of Carbon Fiber Reinforced PEEK Composite Through Double Reinforcement with MWCNTs

Abstract In this study, a double reinforcement method relied on multiwalled carbon nanotubes (MWCNTs) to significantly enhance the strength and fracture toughness of carbon fiber-reinforced thermoplastics (CFRTPs) was demonstrated. MWCNTs were first grafted onto carbon fiber surfaces via nitric acid treatment and silane coupling. Additional MWCNTs were dispersed into a polyether ether ketone (PEEK) thermoplastic matrix. The synergistic effects of the fiber reinforced and matrix-incorporated MWCNTs improved the interlocking network and nanoscale bridging characteristics. The interlaminar shear strength (ILSS) substantially increased by 63.39% from 60 MPa for the baseline to 98.2 MPa for the optimized double reinforcement configuration. The fracture toughness measured by double cantilever beam tests increased by 61.7% from 746.2 J/m² to 1206.7 J/m². Scanning electron microscopy images revealed enhanced energy dissipation mechanisms with nanotube pull-out and crack deflection attributes. The double reinforcement method developed here via the incorporation of MWCNTs into the fiber and matrix phases significantly enhanced the ILSS, fracture toughness, and damage resistance of the CFRTP composites without detrimentally impacting the baseline tensile strength.