Cationic photocured epoxy nanocomposites filled with different carbon fillers

Abstract

In this work, the effect of several carbon fillers, exfoliated graphite (EG), functionalized graphene sheets (FGS), multi-walled carbon nanotubes (MWCNTs), and oxidized multi-walled carbon nanotubes (f-MWCNTs), were compared on the curing process and physical properties of a cationically photocurable epoxy resin. The extent of the photopolymerization was monitored by Real-Time FTIR spectroscopy. It was found that all the nanofillers induced a delaying of the curing reaction probably due to a shielding effect as well as to an increase of the viscosity by the nanofiller. All the systems showed an electrical percolation threshold, but with MWCNTs was attained at a lower concentration (< 0.1 wt.%). In addition, FGS were the most efficient filler for epoxy resins, deduced by the dynamic mechanical and microindentation measurements. An increase of more than 20 ºC in the glass transition temperature was observed with the addition of 1 wt.% of FGS.

Enhanced interfacial interaction of epoxy nanocomposites with activated graphene nanosheets

“…Afterwards, the composite strength decreased with further increasing the TEG content. The results were in good agreement with the literature . A possible strengthening mechanism of TEG was the fact that the wrinkled surface of TEG at the nanoscale likely results in an enhanced mechanical interaction with the epoxy chains and, consequently, a strong interaction .…”

“…It is possible to observe that nanocomposites showed always higher T g values in comparing to the neat cured epoxy, evidenced by the shift of the maximum of tanδ peaks, together with a decrease of the damping. It is well known that in particulate‐filled polymers, the addition of rigid fillers can hinder the polymer chain movements and improve the crosslink density, leading to a damping decrement and a shift of T g values to higher temperatures . In this study, a significant reduction of damping (here evaluated as tanδ max ) was observed in the nanocomposites, together with a strong increment in T g values.…”

Cationic UV-Curing: Technology and Applications

“…Viscoelastic characterization of the composites showed that the filled materials always had higher T g values compared to the neat cured systems. It is noteworthy that all the fillers presented a reinforcing effect with an concomitant increase in the surface hardness values as shown by microindentation tests . In another publication, the same author investigated the effect of FGS in epoxy coatings cured by cationic photopolymerization .…”

Carbon Nanotube-Based UV-Curable Nanocomposite Coatings

“…This functionalization is known to enhance the interface and loadtransfer in CNTs/polymer nanocomposites. Commonly, solution method, a combination of dispersing CNTs in a liquid medium by sonication, mechanical, and magnetic stirring mixing by the polymer solution, and finally evaporating solvents is suggested to prepare a CNT-based UV-curable nanocomposite [7,19,54].…”