Abstract

In the present work the influence of the graphene type (GNP) and the different crosslinking agent ratios in the curing of graphene-epoxy dispersions and in the glass transition temperature (Tg) of the formed nanocomposite is studied. The epoxy resin type DGEBA (LY) has been crosslinked with an aromatic polyamine (XB). Two types of graphene have been used: one non-functionalized (GNPn) and another functionalized with amino groups  (GNPNH2). In the two systems, 5 compositions with different XB / LY ratios have been studied and, the content of graphene has been varied (6 and 10% by weight). The curing reaction has been studied by Differential Scanning Calorimetry. It has been observed that the presence of graphene accelerates the curing reaction and that the enthalpy of reaction depends on stoichiometry and graphene content. It has also been found that the variation of the Tg of the material with the stoichiometry, depends on the curing protocol.

Abstract

In this paper we study the influence of the type of graphene (GNP) and the different ratios of the crosslinking agent (XB)-resin epoxy (LY) on the thermo-mechanical properties of epoxy-graphene nanocomposites (GNP). Epoxy/GNP nanocomposites have been prepared using two different types of graphene: one non-functionalized (GNPn) and one amino functionalized graphene (GNPNH2). The content of graphene has been 6% and 10% by weight. The thermo-mechanical properties of the LY-XB thermoset and the nanocomposites have been determined through dynamic mechanical thermal analysis and tensile tests in a universal testing machine. The glass transition temperature and the storage modulus in the elastomeric zone (T>Tg) of the thermoset LY-XB and the nanocomposites have maximum values ​​for slightly rich amine content. The addition of graphene significantly increases the elastic modulus of the nanocomposites compared to the neat epoxy thermoset (LY-XB), both in the vitreous region (T<Tg) and in the elastomeric region (T>Tg). The thermoset LY-XB shows the best strength and toughness for the stoichiometric ratio XB/LY. The addition of graphene leads to more rigid but more fragile materials.