Mechanical properties of aerospace epoxy composites reinforced with 2D nano-fillers: current status and road to industrialization.

High-performance epoxy composites find application in the aerospace industry. Although epoxy is a high-performance polymer, its fracture toughness is compromised due to its highly cross-linked nature. Nanomaterials such as carbon nanotubes (CNTs), graphene derivatives, and inorganic 2-dimensional (2D) nanomaterials are being explored to improve epoxy composites' mechanical properties. Graphene is one of the most popular 2D nano-reinforcing agents for epoxy composites. Following graphene discovery, the research community's attention was brought to various other few-atom thick 2D nanomaterials. Hence, apart from graphene, inorganic nanosheets such as transition metal dichalcogenides (TMDs), hexagonal boron nitride (hBN), etc. , are also being studied as modifiers for enhancing the mechanical performance of epoxy composites. Graphene, TMDs and hBN are known to possess a high aspect ratio, high specific surface area and inherently high mechanical strength and stiffness, contributing to a stronger and tougher composite. Despite that, the challenges associated with these nanomaterials, such as dispersion issues, lack of standardization, underlying health hazards, etc. , have hampered their commercialization. It has been long past a decade since the discovery of graphene, yet there are concerns regarding the lab to industry scale-up, and health and environmental hazards associated with nanomaterials for the fabrication of aerospace composites. This review offers a comprehensive literature survey and a perspective into the possible ways of bridging the gaps between the laboratory research and industrialization of 2D nanosheet-filled epoxy composites.