Preparation and characterization of Epoxy/Carbon nanofiber nanocomposites

Abstract

In this Final Year Project, the effects of functionalization of carbon nanofibres on its mechanical and thermo-mechanical properties were studied. To this end, vapour-grown carbon nanofibres (VGCNF / CNF) were first functionalized via one-step arylation with in situ generated diazonium salts. Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and elemental analysis were used to verify that triazole groups had been grafted onto the surface of the carbon nanofibres. The nanofibres were then incorporated in epoxy thermoset resins to form CNF/epoxy nanocomposites. Tensile testing, fracture toughness testing and dynamic mechanical analysis (DMA) testing were then carried out to determine the effect of functionalization the mechanical and thermo-mechanical properties of the nanocomposite. The data showed that modified CNFs (m-CNF) exhibited superior performance, particularly in terms of toughening. At 0.4 wt% filler loading level, m-CNF/epoxy nanocomposites have 41% and 80% higher critical stress intensity factor (KIc) and critical strain energy release rate (GIc) than neat epoxy resin respectively, versus 27% and 46% higher for p-CNF/epoxy. Experimentally obtained optical microscopy showed that the m-CNF exhibited less agglomeration in the epoxy matrix, while Field Emission Scanning Electron Microscopy (FESEM) data provided evidence of better interfacial interaction between the CNF and epoxy, both of which are posited as key factors for the enhanced mechanical properties exhibited by m-CNF/epoxy nanocomposites.