Mode-II fracture toughness of carbon fiber reinforced polymer composites interleaved with polyethersulfone (PES)/carbon nanotubes (CNTs)

A comprehensive experimental investigation was carried out to evaluate the toughening behavior of polyethersulfone (PES) and carbon nanotubes (CNTs) interleaf with similar thicknesses for carbon fiber reinforced polymer (CFRP) composites under mode II fracture loading. The influence of four different environmental conditions (room temperature, −55 °C, temperature changes between −55 °C and 80 °C, and salt spray) on mode II fracture toughness (GIIC) was discussed. The flexural property of CFRP composites before and after introducing interleaves was employed at room temperature. Effective diffusion of CNTs is a key means to enhance the interlaminar properties of CFRP composites without sacrificing the bending properties. Results show that CNTs and PES/CNT1 (when the CNTs content is 1 wt%) interleaves could enhance the GIIC by 118.4% and 317.81%, respectively. Hybrid PES/CNTs interleaf exhibited higher mode II fracture toughness and greater adaptability to the environment. The fracture behavior was demonstrated with experimental results and related scanning electron microscopy (SEM) images.