Graphene is a two-dimensional nanosheet made up of sp²-hybridized carbon atoms [14]. Single-layer graphene was produced and recognized in 2004 by Andre Geim and Konstantin Novoselov [15], although it was theoretically explored by P. R. Wallace in 1947 and experimentally by Hanns-Peter Boehm and his coworkers in 1962. Graphene has been prepared through various approaches such as graphite exfoliation, graphite mechanical cleavage, chemical vapor deposition, laser techniques, and numerous other organic synthesis routes [16]. Graphene has revealed exceptional structural and physical features. First of all, graphene (a one-atom-thick nanosheet) is the thinnest known material [17]. Moreover, graphene has a high electron mobilization of ~200,000 cm²V⁻¹s⁻¹. It also shows a high thermal conductivity of ~3000–5000 W/mK [18]. The significantly high Young’s modulus of graphene has been observed as 1 TPa, i.e., 200 times stronger than steel [19]. Owing to van der Waals forces, graphene nanosheets possess a wrinkling tendency, and so can easily crumple [20]. To resolve the nanosheet wrinkling and dispersion issues, graphene has been modified to generate functional groups on the surface [21]. Consequently, graphene has been oxidized to form graphene oxide as a modified form with hydroxyl, epoxide, carbonyl, and carboxylic acid functionalities on the surface. Figure 1 portrays the general structures of graphene nanosheets, whereas Figure 2 displays the structures of graphene oxide. The majority of functional groups in graphene oxide have been found as epoxy and hydroxyl functionalities. Graphene has superior characteristics such as mechanical consistency, thermal stability, chemical stability, and electrical and thermal conductivity [22]. The properties of graphene have been further improved through incorporation in nanocomposites. Due to the unique structure and properties, graphene and graphene-derived nanomaterials have been applied in electronics [23,24,25], sensors [26], energy devices [27], membranes [28], etc. In addition, the impact of graphene has also been analyzed for aerospace purposes [29].

For technical and engineering industries, polymeric composites/nanocomposites have revealed several design and property advantages [32]. Before the application of composites, pristine polymers were used in aerospace structural parts [33,34]. Later, the development of composites and nanocomposites was focused on for aerospace purposes [35]. Compared with unfilled polymers, composite/nanocomposite materials showed better thermal and mechanical properties. In this regard, a number of thermoplastics, thermosets, and rubbery matrices have been applied in the space sector [36,37]. Composites/nanocomposites have the advantage of being lightweight in aerospace, relative to metal-based structures [38]. Using low-density materials also decreased the fuel ingestion of the spacecrafts [39,40]. Moreover, these materials have high strength, modulus, toughness, thermal stability, friction resistance, fatigue performance, and shear resistance characteristics [41,42,43]. Consequently, the structural durability and working life of aerospace structures have been improved [44,45,46]. Multifunctional composites/nanocomposites have been found to be valuable in increasing the capability of space structures in bearing shocks and jerks [47,48] and lightning strikes [49], in radiation shielding [50], and as high-temperature stable engine components [51]. In aerospace nanocomposites, carbon nanoparticles (carbon nanotubes, carbon nanofibers, etc.) and inorganic nanoparticles (metal, metal oxide, etc.) have been used as reinforcements [52,53]. In particular, widely used polymer/carbon nanotube nanocomposites have revealed reasonably high heat stability, flame defiance, thermal conductivity, strength, and mechanical stability for aerospace structures [54,55,56]. Nevertheless, research on aerospace-related composites/nanocomposites is continuously growing, in search of new high-performance structures [57].

Graphene and related nanofillers have effectively increased the electrical conductivity, thermal conductivity, and mechanical features of nanocomposites [58,59,60]. For aerospace applications, nanocomposites have been investigated for physical property improvements and morphological profiles [61]. Various thermosetting and thermoplastic polymers have been used to form graphene-derived nanocomposites for aerospace structures [62]. Among thermosetting polymers, epoxy resins have been extensively used in aerospace-related applications [63]. Graphene and related nanofillers have been reinforced in epoxy matrices to enhance the essential conducting, thermal, and mechanical properties [64,65,66]. According to studies, up to 20 wt.% graphene nanofiller contents may increase the high thermal conductivity, toughness, and fatigue resistance properties of epoxy nanocomposites [67,68,69]. Moreover, graphene oxide nanofiller also improves the tensile strength, fatigue resistance, toughness, heat stability, and tribological properties of epoxy matrices [70,71]. Most importantly, epoxy nanocomposites with graphene and related nanofillers have been used in structural components, adhesives, coatings, etc., for aerospace vehicles [72].

Thermoplastic polymers such as polyethylene, polypropylene, poly(methyl methacrylate), poly(vinyl alcohol), and others have been applied in space applications [73]. Suner and coworkers [74] fabricated polyethylene and graphene-oxide-derived nanocomposites for enhanced mechanical stability. The addition of 0.5 wt.% nanofiller significantly improved the mechanical characteristics of the nanocomposites due to matrix–nanofiller compatibility [75]. Song et al. [76] reported on the polypropylene/graphene nanocomposites fabricated using the solution casting and melt method. The conditions and processes involved in the preparation of polypropylene/graphene nanocomposites are displayed in Figure 3. Graphene oxide was obtained from graphite flakes using the Hummers method [77]. Then, graphene oxide was processed through a solution as well as melt routes to form the nanocomposites. The mechanical properties of the polypropylene/graphene nanocomposites are displayed in Table 1. The inclusion of up to 1 wt.% nanofiller content was found to enhance the yield strength and tensile strength of the nanocomposites due to the mechanical interlocking of the polymer chains with the graphene nanostructure. Moreover, the enhanced mechanical properties were attributed to better graphene dispersion and load transfer between the matrix and the nanofiller [78]. Moreover, the increasing graphene loading was found to improve the crystallinity of the nanocomposite due to orderly nanofiller dispersion and interaction with the polymer matrix [79]. Nanocomposites have been found to be valuable for aerospace applications.

Huang and coresearchers [80] produced flame-retardant poly(methyl methacrylate) nanocomposites for aerospace. An in situ method was used to develop the nanocomposites [81]. Graphene and layered double hydroxide were added as intumescent flame retardants in the poly(methyl methacrylate) matrix to enhance the flame retardancy of the matrix. The poly(methyl methacrylate) matrix with the 1 wt.% graphene and 5 wt.% layered hydroxide considerably enhanced the nonflammability properties through improving the limiting oxygen index. Xu et al. [82] developed poly(vinyl alcohol)/graphene oxide nanocomposites via the vacuum filtration procedure. As compared to the Young’s modulus of the neat poly(vinyl alcohol) matrix (2.1 MPa), the addition of 3 wt.% graphene oxide increased the property up to 4.8 GPa (by 128%). Moreover, including 3 wt.% nanofiller boosted the tensile strength by 110 MPa (70%), as compared to the neat polymer (65 MPa). The increase in the mechanical properties was credited to the interfacial interactions in the matrix–nanofiller, leading to relevance in aerospace. Hence, different polymers reinforced with graphene nanofillers have enhanced mechanical, thermal, and conducting profiles and are found to be useful as aerospace materials.

In the aerospace industry, high-performance matrices such as poly(ether ether ketone) (PEEK) [83,84], poly(ether ketone ketone) (PEKK) [85,86], polyetherimide [87], and polysulfone [88] have been found to be desirable due to high mechanical, thermal, and electrical properties. Puértolas et al. [89] fabricated PEEK/graphene nanocomposites using solvent-free melt-blending and injection-molding techniques. The 1–10 wt.% graphene nanofiller was included in PEEK matrix. The inclusion of graphene caused a 60% improvement in the hardness of the material. The coefficient of friction and the wear factor were decreased by 38% and 83%, respectively. Thus, graphene was found to be an important nanofiller to enhance the surface hardness and tribological properties of the PEEK matrix, desirable for aerospace uses. Alvaredo et al. [90] introduced graphene nanoplatelets in PEEK using the melt-blending technique. The 1–10 wt.% nanofiller was included in the PEEK matrix. The inclusion of graphene nanoplatelets enhanced the complex viscosity and rheological behavior of the nanocomposites and they were found to be effective for the space sector. Wang et al. [91] produced PEKK/graphene nanomaterials with enhanced electrical conductivity and mechanical performance, suitable for high-tech industrial relevance. Sun et al. [92] fabricated high-performance polyetherimide/graphene oxide nanocomposites. The inclusion of graphene oxide nanofiller improved the tensile strength and temperature-dependent tensile behaviors of the polyetherimide/graphene oxide nanocomposites. These materials have fine suitability for the space sector. Ionita et al. [93] developed polysulfone/graphene oxide nanocomposites using the phase inversion technique. The inclusion of 0.25–2 wt.% nanofiller was studied. The homogeneous nanofiller dispersion considerably improved the thermal stability of the nanocomposites. Janire Peña-Bahamonde et al. [94] also prepared polysulfone/graphene oxide nanocomposites through the solvent-free extrusion–injection technique. The addition of 3 wt.% nanofiller upsurged the dispersion, rheological properties, and toughness of the nanocomposites. These materials can be feasible candidates for aerospace applications.