Fabrication, Functionalization, and Application of Carbon Nanotube-Reinforced Polymer Composite: An Overview

Abstract

A novel class of carbon nanotube (CNT)-based nanomaterials has been surging since 1991 due to their noticeable mechanical and electrical properties, as well as their good electron transport properties. This is evidence that the development of CNT-reinforced polymer composites could contribute in expanding many areas of use, from energy-related devices to structural components. As a promising material with a wide range of applications, their poor solubility in aqueous and organic solvents has hindered the utilizations of CNTs. The current state of research in CNTs-both single-wall carbon nanotubes (SWCNT) and multiwalled carbon nanotube (MWCNT)-reinforced polymer composites-was reviewed in the context of the presently employed covalent and non-covalent functionalization. As such, this overview intends to provide a critical assessment of a surging class of composite materials and unveil the successful development associated with CNT-incorporated polymer composites. The mechanisms related to the mechanical, thermal, and electrical performance of CNT-reinforced polymer composites is also discussed. It is vital to understand how the addition of CNTs in a polymer composite alters the microstructure at the micro- and nano-scale, as well as how these modifications influence overall structural behavior, not only in its as fabricated form but also its functionalization techniques. The technological superiority gained with CNT addition to polymer composites may be advantageous, but scientific values are here to be critically explored for reliable, sustainable, and structural reliability in different industrial needs.

Keywords: CNT nanocomposites; MWCNT; SWCNT; carbon nanotubes; covalent functionalization; non-covalent functionalization; polymer composites.

Figure 1

(a) The covalent functionalization phenomena at the side and end-caps of CNT structure (reproduced from [33]) and (b) non-covalent functionalization method for polymer wrapping (adapted from [54]).

Figure 1

(a) The covalent functionalization phenomena at the side and end-caps of CNT structure (reproduced from [33]) and (b) non-covalent functionalization method for polymer wrapping (adapted from [54]).

Figure 2

Distribution of micro- and nano-scale fillers: (a) Al₂O₃ particle, (b) carbon fiber, (c) graphene nano-platelets (GNPs), and (d) CNTs. Adapted from [82].

Figure 3

(a) View of micro-compounder with different valves and channels; (b) the schematic representation of a twin-screw extruder for the melt mixing of CNT-reinforced nanocomposites. Adapted from [81,85].

Figure 4

Schematic diagram of the fabrication process for the CNT–epoxy composites: (a) preparation of CNT suspension and (b) preparation of CNT–epoxy composite. Adapted from [96].

Figure 4

Schematic diagram of the fabrication process for the CNT–epoxy composites: (a) preparation of CNT suspension and (b) preparation of CNT–epoxy composite. Adapted from [96].

Figure 5

Schematic of the resin transfer molding process for fabricating CNT/epoxy composites. Adapted from [99].

Figure 6

Schematic diagram showing aligned CNT sheet processing: (a) drawing and winding; (b) drawing, winding, and pressing (reproduced from [108]). (c) CNT sheet processing: (1) drawing and winding technique; (2) drawing, winding, and pressing process; (3) non-pressed CNT sheet; and (4–6) pressed CNT sheets under corresponding press load. Reproduced from [107].

Figure 7

Schematic diagram for the shear mixing technique. Reproduced from [32].

Figure 8

Schematic representation of in situ polymerization process. Reproduced from [90].

Figure 9

SEM micrographs of tensile fracture surface of CNT/polyimide composite. Reproduced from [104].

Figure 10

Classifications of three different states concerning the percolation theory-based electrical conductance transition for CNT-filled polymer nanocomposites. Reproduced from [204].

Figure 11

Application of CNT–polymer composites.