Fracture toughness enhancement of fuzzy CNT-glass fiber reinforced composites with a combined reinforcing strategy

Low interlaminar mechanical properties is the foremost drawback of glass fiber reinforced composites (GFRPs). Hierarchical nanoparticles on fibers (e.g. carbon nanotubes (CNTs)) can improve interlaminar properties of composites with negligible weight increase because of excellent mechanical properties, and low density. Interlaminar properties of composites can be enhanced with the well-dispersed CNTs in polymer matrices as it facilitates load transfer from matrix to fibers. This paper investigates the mechanical properties of CNT-reinforced GFRPs. Two reinforcing strategies were studied as dispersion of CNTs in epoxy matrix and direct growth of CNTs onto glass fibers (GFs), simultaneously. The former is referred to as nanotube-reinforced composites (NRCs) while the latter is known as fuzzy architectures. Furthermore, the combination of NRCs and fuzzy glass fibers (F-GFs), also known as fuzzy nano-reinforced composites (F-NRCs), is used to fabricate composites and identify the reinforcing capabilities through both methods. Mechanical properties are investigated by Mode-I fracture toughness and unidirectional (UD) composite tensile tests. Even though NRCs and F-NRCs yield similar enhancements in the propagation fracture toughness as 113% and 119%, respectively, the tensile strength of F-NRCs is decreased by 24% due to heat treatment during the CNT synthesis.