Poly(lactic acid)/graphene and poly(lactic acid)/carbon nanotube nanocomposites were prepared by an easy and low-cost method of melt blending of preliminary grinded poly(lactic acid) (PLA) with nanosized carbon fillers used as powder. Morphological, structural and mechanical properties were investigated to reveal the influence of carbon nanofiller on the PLA–based composite. The dependence of tensile strength on nanocomposite loading was defined by a series of experiments over extruded filaments using a universal mechanical testing instrument. The applying the XRD technique disclosed that compounds crystallinity significantly changed upon addition of multi walled carbon nanotubes. We demonstrated that Raman spectroscopy can be used as a quick and unambiguous method to determine the homogeneity of the nanocomposites in terms of carbon filler dispersion in a polymer matrix.

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This paper proposes the design of a new graphene nano-modified formulation to enhance the mechanical performance of structural adhesives. Well-characterized graphene platelets, produced through an effective approach for bulk production and morphology control, were embedded at different contents inside an epoxy adhesive based on tetraglycidylmethylene dianiline (TGMDA). The adhesive formulations were used to manufacture bonded joints, according to ASTM 2095, to analyze the effect of graphene platelets on the tensile strength of the joints. The effect of incorporating graphene in the adherents was also considered. Epoxy adhesives filled with graphene at a concentration of 1 wt% significantly enhanced the mechanical behavior of the bonded joints. Only in the case of unfilled adherents, the inclusion of 4 wt% graphene did not have a significant effect on the mechanical performance. This is likely due to the agglomeration of nanofillers causing heterogeneity in large domains at the interface between adherents and adhesives. The effect of graphene incorporation in the adherents, acting on the chemical compatibility between adhesives and adherent surfaces, led to a considerable increase in tensile strength in comparison with the corresponding joints with unfilled adherents. This beneficial effect is most probably due to the cumulative effects of intermolecular interactions between the graphene platelets and resin networks

Few layer graphene oxide (GO) nanosheets were prepared by a very fast modified Hummers method and widely characterized. Avoiding further chemical reactions, trying to take advantage of the easy exfoliation of GO favoring the formation of a tribofilm, and using a methodology well known to the lubricant industry, they were added to a mineral oil by the help of a dispersant. The tribological behaviour of GO in mineral oil was investigated under a wide spectrum of conditions, from boundary and mixed lubrication to elastohydrodynamic regimes. A ball on disc setup tribometer has been used to verify the friction reduction due to nanosheets dispersed in mineral oil. Their good friction and anti-wear properties may possibly be attributed to the small and extremely thin laminated structure, which offer lower shear stress and prevent interaction between metal interfaces. Furthermore, the results clearly prove that graphene platelets in oil easily form a protective film to prevent the direct contact between steel surfaces and, thereby, improving the frictional behaviour of the base oil. This evidence is also related to the frictional coefficient trend in boundary regime.

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