Curing kinetic of an epoxy resin reinforced with amino-functionalized MWCNTs has been studied by DSC and the obtained results were explained through morphological studies carried out by SEM, TEM, FEG-SEM, and molecular simulation tools. The presence of MWCNTs in the curing reaction induces a retardation effect of curing reaction and a decrease of the reaction heat. Both are associated with the adsorption of curing agent molecules inside carbon nanotubes, which was proved through the application of electron microscopic techniques and molecular simulation tools. It has been also demonstrated that there is a chemical reaction between amine groups anchored to the nanotubes and oxirane rings of epoxy monomer, which improves the nanoreinforcement/matrix interfacial adhesion, appearing a chemical interphase. The glass transition temperature ( ) of epoxy matrix increases by the addition of MWCNTs due to the restriction of its mobility. 1. Introduction Epoxy resins are commonly used as polymeric matrices in high-performance composites. Carbon nanotubes (CNTs) are promising fillers to improve their mechanical, thermal and electrical behaviour [1, 2]. Numerous studies have been published about the fabrication and characterisation of CNT/epoxy nanocomposites [3–5]. The most of researches show moderate results regard to the theoretically expected ones. The properties of nanocomposites are improved regarding those showed by neat epoxy resins but they are not usually higher than the ones of conventional microscale composites. Poor dispersibility and high chemical inertness of as-synthesised carbon nanostructures can be the main processing limitations. In order to increase the compatibility between CNTs and epoxy matrix, an initiative consists on the introduction of polar groups on the surfaces of nanotubes [6, 7]. The nanoreinforcements are covalent functionalized through reactive linker molecules, which can later react with functional groups of the matrix, providing interfaces of high covalent integrity. In particular, amino-functionalized CNTs are being widely investigated [8–10] as fillers of epoxy resins. The thermal and mechanical characterisation of epoxy nanocomposites reinforced with amino-functionalized CNTs has been already tackled by several authors, showing some contrary results. In concrete, some works [9, 10] show that the glass transition temperature ( ) of epoxy matrix increases by the addition of amino-functionalized carbon nanotubes. This fact has been associated to the lower mobility of the epoxy moiety when it reacts with amino groups immobilized
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