A Comprehensive Review on CNTs and CNT-Reinforced Composites: Syntheses, Characteristics and Applications

Since their first synthesis, carbon nanotubes (CNTs) gained remarkable research interest owing to their astonishing mechanical properties and extensive range of potential applications in various sectors, such as aerospace, automobile, biomedical, defence, energy, etc. This paper covers numerous characterization techniques, synthesis approaches and properties of the CNTs, reported by earlier researchers in the past. The technological and industrial needs for the development of lightweight nanocomposites have led to the significant advancements in the preparation of CNT-reinforced composites. In preliminary sections, the properties and applications of the CNT-reinforced nanocomposites are elaborated along with the issues related to their preparation. Here, various nanotubes synthesis processes, such as arc discharge, laser ablation and chemical vapour deposition, are exemplified with the support of published works. Furthermore, we have also addressed the several surface modification techniques of CNTs, such as purification, functionalization and dispersion, which make this review novel and exhaustive. In order to address the limitations and challenges incurred during the preparation of various CNT-reinforced polymer/metal matrix composites, an extensive collection of the published literature is reported and discussed, thoroughly. Based on this exhaustive review, some specific observations are made which would facilitate upcoming researches to explore the research opportunities in the preparation of CNTs and CNT-reinforced composites and their potential applications for the high-performance structures/components.