The Potential of Graphene Nanoplatelets in the Development of Smart and Multifunctional Ecocomposites

Abstract

Graphene and its derivatives have shown outstanding potential in many fields and textile/composites industry are not an exception. Giving their extraordinary properties, Graphene Nanoplatelets (GNPs) are excellent candidates for providing new functionalities to fibers and composites. In this work, natural fabrics (flax) were functionalized with chitosan (CS) based polymeric formulations of GNPs to develop fibrous systems with electrical properties as well as other functionalities. One of the greatest disadvantages of using carbon-based materials for fabrics’ impregnation is their difficult dispersion. Therefore, several polymers were used as matrices, binding and dispersive agents including chitosan, polyethylene glycol (PEG), and glycerol. All the systems were characterized using several techniques that demonstrated the presence and incorporation of the GNPs onto the composites. Besides their characterization, considering their use as smart materials for monitoring and sensing applications, electrical properties were also evaluated. The highest value obtained for electrical conductivity was 0.04 S m−1 using 2% of GNPs. Furthermore, piezoresistive behavior was observed with Gauge Factor (GF) of 1.89 using 0.5% GNPs. Additionally, UV (ultraviolet) protection ability and hydrophobicity were analyzed, confirming the multifunctional behavior of the developed systems extending their potential of application in several areas.

Smart Fibrous Structures Produced by Electrospinning Using the Combined Effect of PCL/Graphene Nanoplatelets

“…The electrical conductivity values, calculated as described previously using the two-wire method, are shown in Table 2 after each water treatment cycle and for the different GNPs concentrations. As can be verified in the results shown in Table 2, as the presence of GNPs in the samples increased (higher concentration), the electrical conductivity also increased considerably, corroborating the well-known electrical properties of these particles [6].…”

“…This bulge will generate a pseudo-magnetic field, consequently decreasing the electrical resistance, which means that the electrons will be scattered by the compressed region. This behavior is reflected and quantified by the GF values for piezoresistive materials [6] All the piezoresistive behavior tests were performed after the successive washing and drying treatments, with the objective to ensure the highest stability as possible in the results. In addition, 50 consecutive compression cycles were carried out, considering only the last 10 measurements in order to ensure the correct material relaxation and thus obtain the most reliable results possible.…”

“…The sensitivity of the sensors can be expressed by the GF. The GF values were calculated using Equation (6). These results are presented on Table 3 and were calculated as the average of 10 ascending and descending cycles.…”

“…There are many examples of smart systems incorporated onto textiles using hardware, such as cables and electronic components, that make them uncomfortable for the users. Thus, effort has been made to give fibrous structures themselves electrical properties without adding extra electronical materials to the textiles [5,6]. In this sense, researchers are continuously working on developing innovative fibrous structures with these kinds of characteristics [7].…”

“…High sensitive damage sensors based on glass fiber fabrics coated with functionalized GNPs were developed by Moriche et al [24]. Pereira et al reported the development of a piezoresistive sensor based on the combined effect of GNPs, flax fabrics, and biopolymers, such as chitosan and polyethylene glycol [6]. Souri et al also developed flexible and wearable strain sensors by the coating of flax fabrics with GNPs using the ultrasonication technique [25].…”