Funcionalização não covalente de nanotubos de carbono e grafeno para aplicação em compósitos carbono/epóxi

Abstract

The addition of graphene and carbon nanotubes (CNT) as nanofillers in composite materials to improve its mechanical properties has been reported by different authors. However, these structures have the tendency to agglomerate when the energy provided by the dispersion process is removed, due to the van der Waals forces between nanotubes and graphene sheets. One possible solution to overcome this problem is the non-covalent functionalization of these nanostructures by the usage of surfactants. This research goal is to analyze the surfactant effect on the overall behavior of carbon/epoxy composites nanomodified by graphene and carbon nanotubes. Multi-layered graphene and multiwall carbon nanotubes were dispersed with the surfactants Sodium dodecylbenzenesulfonate (SDBS) and Polyoxyethylenenonylphenyl ether (IGEPAL® CO-890). The morphological and structural analysis was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The mechanical properties were evaluated by tensile tests (ASTM D 3039), three point bending test (ASTM D 790) and tensile tests of dog bone shape specimens (ASTM D638). The stiffness values obtained in both tensile and bending tests were statistically equal to the blank, indicating that the stiffness seems to be insensible to functionalized nanostructures. Nevertheless, an improvement on the ultimate strength of 23.5% for tensile tests and of 11.5% for bending tests was observed when the non-ionic CO890 surfactant was employed. The results of the dog bone tensile tests indicate a change on epoxy behavior from brittle to ductile. The morphological and structural analysis results indicated that the carbon nanostructures were well functionalized by the surfactants used.