Interlaminar fracture toughness and viscoelastic properties of nanofiller-modified woven CFRP composites

Interlaminar fracture behavior and viscoelastic properties play a critical role in determining the service performance of woven carbon fiber-reinforced polymer (WCFRP) composites. In this work, three nanofillers with distinct morphologies, including particle-type nanozinc oxide (nano-ZnO), rod-type carbon nanotubes (CNTs), and flake-type graphene nanoplatelets (GNPs), were incorporated into WCFRP laminates. Double cantilever beam (DCB) and end-notched flexure (ENF) tests, along with dynamic mechanical analysis (DMA), were performed to evaluate the Mode I and Mode II interlaminar fracture toughness and viscoelastic behavior. Results indicated that CNTs exhibited the most effective toughening under Mode I loading, yielding an improvement of 24.46%. While nano-ZnO showed limited enhancement in Mode I interlaminar fracture toughness, it increased the Mode II toughness by 29.89%. GNPs displayed a distinct concentration-dependent effect on interlaminar properties, with the 0.5 wt.% GNPs modification achieving the optimal toughening efficiency under Mode II conditions, representing an increase of 70.86%. DMA results further revealed that GNPs significantly enhanced the stiffness and thermal stability of the composites, whereas CNTs were more conducive to improving damping performance. Conversely, nano-ZnO exerted a negligible influence on the overall viscoelastic properties. Combined with microstructural characterization of the nanofillers and fracture surfaces, the potential regulatory mechanisms of different nanofillers on the interlaminar performance were comparatively analyzed. Graphical abstract