Banca de QUALIFICAÇÃO: GINA MARITZELL COLMENARES JIMENEZ

Study of the effect of graphene oxide and functionalized graphene oxide on the Epoxy/anhydride system

electrochemical exfoliation of graphite, graphene oxide, epoxy resin, kinetic study of cure, mechanical properties

The development of new materials, such as fiber-reinforced composites, has been a first step towards the growth of the construction industry. The introduction of composites with reinforcing fibers (natural, glass, polymeric, etc.) in the civil industry aims to increase efficiency and effectiveness in the construction. Among the many advantages we highlight, low cost, low density and abrasiveness. Among the many applications we mention the replacement of steel rebar with fiber-reinforced composites. The processing technique is pultrusion. Therefore, increasing the modulus of the polymer matrix is important for the mechanical strength of these fiber-reinforced composites. In recent decades, graphene or graphene oxide in epoxy matrices has been studied with a view to increasing the modulus of elasticity. The aim of this Doctoral Thesis is to study the effect of graphene oxide (GO) and functionalized graphene oxide (f-GO) on the mechanical properties of epoxy resin. GO was obtained through electrochemical exfoliation of graphite in an acidic medium.  The GO was then characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Finally, OG concentrations of 0.10; 0.13, 0.2 and 0.5% by weight were physically mixed in Litestone 3200 E epoxy resin. The study of the effect of OG on the curing reaction of the resin with Listestone 2131H hardener was carried out by differential scanning analysis (DSC ). The study was carried out using the dynamic method and the activation energies (Ea) calculated using the Kissinger and Osawa method. Test specimens to determine glass-rubber transition temperature (tg) and mechanical properties were prepared using the manufacturer's curing cycle. The results obtained show that Ea increases with the presence of GO in the matrix, for low levels, increasing for higher concentrations. Tg did not change significantly with the presence of GO. The mechanical properties show a slight improvement at low concentrations of GO in the matrix.