In this work, a novel nanomaterial deposition technique involving the triboelectrification (TE) of glass fibers (GF) to create attractive charges on their surface was investigated. Through TE, continuous GF were positively charged thus, attracting negatively charged graphene oxide (GO) nanoparticles dispersed in a solution. The electrical charges on the glass fibers surface increased with the intensity of the TE process. The deposited GO coating was then chemically treated to obtain reduced graphene oxide (rGO) on the surface of GFs. The amount of coating obtained increased with the GO solution concentration used during the deposition process, as revealed by FESEM analysis. However, the same increment could not be noticed as a function of the intensity of the process. Both uncoated and coated GF were used to obtain single fiber microcomposites by using a bicomponent epoxy matrix. The fiber/matrix interfacial shear strength was evaluated through micro debonding tests, which revealed an increment of fiber/matrix adhesion up to 45% for rGO coated GF in comparison to the uncoated ones. A slight improvement in the electrical conductivity of rGO coated fibers through TE compared to conventional dip coating was also observed in terms of volumetric resistivity by a four-point probe setup.

The elevated brittleness of commercial grades of poly(lactic acid) (PLA) may limit their use in several engineering applications. Therefore, the aim of this work is to develop a PLA-based material possessing well-balanced stiffness and toughness. Composites were prepared by blending PLA with increasing contents (from 10 to 30 wt%) of a thermoplastic polyurethane (TPU) and a fixed concentration (5 wt%) of carbon fibers (CFs), to tune the mechanical properties of the resulting materials. In order to increase the interfacial adhesion between CFs and polymeric phase, CFs were subjected to an acidic modification, by treating them in solution of H 2 SO 4 and HNO 3 . The prepared composites were characterized from a chemical, rheological, morphological, and thermomechanical point of view. Fourier transform infrared spectroscopy showed that the fiber surface reactivity was significantly enhanced by the acid treatment, with the introduction of reactive functional groups on CFs. Rheological and dynamic-mechanical tests confirmed that the introduction of acid-treated CFs implied strong fiber-matrix interactions. Thanks to the presence of the acid treated CFs, an important increase in tensile modulus and maximum stress was obtained for all the compositions. In particular, samples containing 10 wt % of TPU showed +74% tensile modulus and +43% maximum stress with respect to the unfilled blends. Moreover, the elongation at break of PLA was significantly improved (+81%) with the addition of 30 wt% of TPU. It was therefore demonstrated that the adopted approach could be effective for the preparation of novel PLA-based materials with tailorable and well-balanced properties that could find application in various technological fields.

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