This review critically examines the current state of graphene reinforced metal (GNP-MMC) and ceramic matrix composites (GNP-CMC). The use of graphene as reinforcement for structural materials is motivated by their exceptional mechanical/functional properties and their unique physical/chemical characteristics. This review focuses on MMCs and CMCs because of their technological importance for structural applications and the unique challenges associated with developing high-temperature composites with nanoparticle reinforcements. The review discusses processing techniques, effects of graphene on the mechanical behaviour of GNP-MMCs and GNP-CMCs, including early studies on the tribological performance of graphenereinforced composites, where graphene has shown signs of serving as a protective and lubricious phase. Additionally, the unique functional properties endowed by graphene to GNP-MMCs and GNP-CMCs, such as enhanced thermal/electrical conductivity, improved oxidation resistance, and excellent biocompatibility are overviewed. Directions for future research endeavours that are needed to advance the field and to propel technological maturation are provided.

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Graphene-nanoplateles (Gr) and multiwalled carbon nanotubes (CNTs) reinforced epoxy based composites were fabricated using ultrasonication, a strong tool for effective dispersion of Gr/CNTs in epoxy. The effect of individual addition of two different nanofillers (Gr and CNT) in epoxy matrix, for a range of nanofiller content (0.1-1 wt %), has been investigated in this study. This study compares mechanical and thermomechanical behavior of Gr and CNT reinforced epoxy. Gr reinforcement offers higher improvement in strength, Young's modulus, and hardness than CNT, at 0.2 wt %. However, mode-I fracture toughness shows different trend. The maximum improvement in fracture toughness observed for epoxy-Gr composite was 102% (with 0.3 wt % loading of Gr) and the same for epoxy-CNT composite was 152% (with 0.5 wt % loading of CNT). Thorough microstructural studies are performed to evaluate dispersion, strengthening, and toughening mechanisms, active with different nanofillers. The results obtained from all the studies are thoroughly analyzed to comprehend the effect of nanofillers, individually, on the performance of the composites in structural applications.

Fascicular rearrangement of an injured peripheral nerve requires reconnection of nerve sprouts from anterior and Büngner bands from distal sides of the lesion, failing to which leads to inefficient regeneration of the injured nerve. However, existing neural scaffolds have limited neuroregeneration efficiency because of either the lack of alignment of fibers and a conductive second phase, leading to compromised electrical conductivity, or the lack of extracellular matrix components and in vivo validation. The present study reports a biocompatible, multiwall carbon nanotube (MWCNT)-reinforced, anisotropically conductive, electrospun, aligned nanofibrous scaffold, ensuring maximal peripheral nerve regeneration. Electrospinning parameters were modulated to deposit random and parallel fibers in separate scaffolds for comparative analysis on the effect of fiber alignment on regeneration. Both types of scaffolds were reinforced with MWCNTs to impart electrical conductivity. Nonreinforced scaffolds were nonconductive. In this comparative study, MWCNT-reinforced, aligned scaffolds showed better tensile property with increased conductivity along the direction of alignment, thereby ensuring an escalated neural-regeneration rate. Collectively, in vitro studies established the scaffolds to be highly biocompatible, promoting cell growth and proliferation. With 85% more anisotropic conductivity in the direction of the alignment and the degradation kinetics tuned to the regeneration regime, the MWCNT-reinforced, aligned scaffold efficiently healed injured sciatic nerves in rats within 30 days. Rigorous revivification of the tissue was due to coordinated Wallerian degeneration and expedited guided axonal regeneration. Structural and functional analysis of nerves in vivo showed the aligned, MWCNT-reinforced scaffold to be very efficient in peripheral sciatic nerve regeneration. This study notes the efficacy of the coaxially aligned, MWCNT-reinforced neural scaffold, with a capability of establishing remarkable advancement in the field of peripheral neural regeneration.