Insights into the effect of fiber-matrix interphase physiochemical-mechanical properties on delamination resistance and fracture toughness of hybrid composites

The characteristics of the formed fiber-matrix interphase play a decisive role during fracture of fiber reinforced composites. Herein, we experimentally investigate the influence of fiber-matrix interphase on the fracture toughness of fiber-reinforced composites. Carbon fiber is modified with nanoparticles having different physical and chemical features, including functionalized carbon nanotubes (fCNTs), cellulose nanocrystals (CNCs), and hybrid CNC-CNT, and the effect of chemical and mechanical properties of the fiber-matrix interphase and fiber surface topology on the mode I and mode II delamination resistance of carbon fiber/epoxy composites is studied. The objective of this study is to fundamentally understand the relationship of fiber-matrix interphase properties and fracture toughness. It is observed that fiber-matrix interfacial strength depends on the width and chemical properties of the interphase zone. CNC-CNT spans the interfacial zone enhancing the interfacial strength by 76%, allowing the matrix to have a more effective contribution during the fracture. The stronger interphase subse-quently results in 183% improvement in mode I and 75% improvement in mode II interlaminar fracture toughness of the composite.