## 5 Advanced Reinforced Graphene Nanoplatelet-Based Bio-Nanocomposites  
Graphene-based reinforced nanocomposites showed a prominent role in the field of advanced materials [137, 138, 139, 140, 141]. The outstanding mechanical properties of single layer graphene, GnPs and GO, led to a new generation of improved plastic-based structural materials [142, 17, 143]. For example, these 2D carbon-based fillers are attractive for the realization of next generation sporting goods [144], concrete [145], anti-corrosion coatings [146], automotive lightweight components [147], structural elements in aerospace [148], and wind turbine designs [149]. In particular, GnP powder is already produced at large scales and at a low price compared with single-layer graphene, and as such, is more appealing for the composite market [150]. Furthermore, GnPs were already selected as  
Figure 14: Haptic sensor functionality under elongation of elastomeric conductive inks sprayed on both sides of nitrile glove pieces. (**a**) Graphic representation of the CnF- and GnP-based tactile sensor at 0% elongation (L0) and at 100% stretch (L100); (**b**) device performances at consecutive elongation steps. \(\Delta\)C\({}_{\text{i}}\) and \(\Delta\)C\({}_{0}\) represent the capacity deviation with touch under elongation and at 0% stretch, respectively. Reprinted with permission from Advanced Science 5, 2, 1700587. Copyright 2017 Wiley. nanofilers for toughening polymeric materials, since they are strong, and present lower defect concentrations compared to GOs [151]. GnPs integrate the excellent mechanical characteristics of carbon nanotubes with the multi-flakes structure of clays, which can impart superior structural property improvements [150]. Indeed, they were shown to perform significantly better than these nanofillers in enhancing the mechanical properties of nanocomposites such as tensile strength, elastic modulus, fracture toughness, fracture energy, and resistance to fatigue and crack growth [65; 152], due to their higher compatibility with polymers matrix [153]. To obtain an effective reinforcement, a crucial requirement is the homogeneous dispersion of the flake-like filler inside the polymer matrix [17; 143; 154; 155; 156; 157], as schematically shown in Figure 15a. However, such conditions are necessary but not sufficient. Indeed, also flake dimensions (lateral size and thickness), alignment, and chemical interaction with the matrix (see Figure 15b) need to be taken into account [154; 156; 157; 158; 24]. Furthermore, a recent paper by [PERSON] et al. [159] investigates in depth the mutual interaction between graphene-based materials and the hosting matrix. Through the examination of hundreds of papers on graphene composites, they demonstrated that the fillers modulus is dependent on the polymer matrix. In particular, the GnPs modulus is larger when the filler concentrations are reasonably low and the matrix is more rigid. This implies that the common hypothesis that the nanoflake modulus is independent of the matrix is not correct. Many works have been published so far dealing with the incorporation of graphene, graphene oxide or GnPs inside traditional synthetic and long-lasting plastics. Several reviews are already available on these topics [17; 141; 153; 137; 138; 139; 140; 141; 151; 20; 21; 21; 22; 23; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53]. In contrast, reviews centered on the reinforcement of bioplastics with graphene-based materials are still rare [160]. Biopolymers are biodegradable; thus, they contribute only slightly to environmental pollution [161; 162]. They are constantly gaining interest, considering that they could gradually substitute oil-based, polluting, synthetic polymers [163; 164; 165]. Nevertheless, a broad spread-out of these green plastics is often limited, taking into account their poor mechanical properties [162; 163; 164].