C. Esposito Corcione

Graphene oxide as a catalyst for ring opening reactions in amine crosslinking of epoxy resins

The influence of different graphite-based nanofillers on epoxide ring opening reactions, as induced by amines for diglycidyl ether of bisphenol A (DGEBA), is studied. Direct kinetic studies, with full chemical characterization and quantitative evaluation of the low molecular mass products, for reactions of DGEBA with primary and secondary monoamines as well with alcohols, are conducted. Moreover, the kinetic behavior of a commercial epoxy resin based on DGEBA and a diamine, leading to crosslinked insoluble networks, is studied by indirect methods, such as differential scanning calorimetry (DSC) and rheometry. The reported results show a relevant catalytic activity of graphene oxide on epoxy resin crosslinking by amines. For instance, for a graphene oxide content of 3 wt%, the exothermic crosslinking DSC peak is shifted (upon heating at 10 °C min−1) from 113 °C down to 96 °C, while the gel time at 50 °C is reduced by a factor of 2.5. This behavior is due to the ability of graphene oxide to catalyze primary amine–epoxy, secondary amine–epoxy and mainly hydroxyl–epoxy additions.

Water Vapor Permeability of Clay Nanocomposites Based on Amorphous PET

In this work nanocomposites based on amorphous poly(ethylene terephthalate) (PETg) were developed using melt intercalation. X-ray analysis performed on the PETg nanocomposites showed that intercalation and exfoliation took place during static mixing. The water vapor permeability of PETg nanocomposites was correlated to the volume fraction of the impermeable inorganic part of the omMMT.

Cure reaction of epoxy resins catalyzed by graphite-based nanofiller

A significant effort was directed to the synthesis of graphene stacks/epoxy nanocomposites and to the analysis of the effect of a graphene precursor on cure reaction of a model epoxy matrix. A comparative thermal analysis of epoxy resins filled with an exfoliated graphite oxide eGO were conducted. The main aim was to understand the molecular origin of the influence of eGO on the Tg of epoxy resins. The higher Tg values previously observed for low curing temperatures, for epoxy resins with graphite-based nanofillers, were easily rationalized by a catalytic activity of graphitic layers on the reaction between the epoxy and amine groups of the resin, which leads to higher crosslinking density in milder conditions. A kinetic analysis of the cure mechanism of the epoxy resin associated to the catalytical activity of the graphite based filler was performed by isothermal DSC measurements. The DSC results showed that the addition of graphite based filler greatly increased the enthalpy of epoxy reaction and the re...

Epoxy Resin Catalyzed by Graphite-Based Nanofillers

Abstract Graphene stacks/epoxy nanocomposites were produced and characterized in order to analyse the effect of different graphene precursors on cure reaction of a model epoxy matrix. A kinetic analysis of the cure mechanism of the epoxy resin associated to the catalytical activity of the graphite based fillers was performed by isothermal DSC measurements. The DSC results showed that the addition of all graphite based fillers greatly increased the enthalpy of epoxy reaction and the reaction rate, confirming the presence of a catalytic activity of graphitic layers on the crosslinking reaction between the epoxy resin components (epoxide oligomer and di-amine). A kinetic modelling analysis, arising from an autocatalyzed reaction mechanism, was finally applied to isothermal DSC data, in order to predict the cure mechanism of the epoxy resin in presence of the graphite based nanofiller.

Structural relaxation of amorphous PET matrix nanocomposites

The aim of the present paper is the evaluation of the degree of dispersion and intercalation of monodimensional nanofillers in an amorphous thermoplastic matrix. Organically modified montmorillonites (omMMT) were used as monodimensional nanofillers, whereas amorphous PET copolymer (PETg) was used as matrix.