In Situ Exfoliation of Graphene in Epoxy Resins: A Facile Strategy to Efficient and Large Scale Graphene Nanocomposites

Abstract

Any industrial application aiming at exploiting the exceptional properties of graphene in composites or coatings is currently limited by finding viable production methods for large volumes of good quality and high aspect ratio graphene, few layer graphene (FLG) or graphite nanoplatelets (GNP). Final properties of the resulting composites are inherently related to those of the initial graphitic nanoparticles, which typically depend on time-consuming, resource-demanding and/or low yield liquid exfoliation processes. In addition, efficient dispersion of these nanofillers in polymer matrices, and their interaction, is of paramount importance. Here we show that it is possible to produce graphene/epoxy nanocomposites in situ and with high conversion of graphite to FLG/GNP through the process of three-roll milling (TRM), without the need of any additives, solvents, compatibilisers or chemical treatments. This readily scalable production method allows for more than 5 wt % of natural graphite (NG) to be directly exfoliated into FLG/GNP and dispersed in an epoxy resin. The in situ exfoliated graphitic nanoplatelets, with average aspect ratios of 300-1000 and thicknesses of 5-17 nm, were demonstrated to conferee exceptional enhancements in mechanical and electrical properties to the epoxy resin. The above conclusions are discussed and interpreted in terms of simple analytical models.

Graphene-Reinforced Biodegradable Resin Composites for Stereolithographic 3D Printing of Bone Structure Scaffolds

“…SEM was conducted to assess the morphology and in particular the length (defined as the longest lateral dimension) of the graphene, FLG, GNP. Please refer to our previous publication for more information [21]. Optical microscope (OM, Leica M205 A, Germany) was applied to observe the surface appearance and the distribution of bubbles.…”

“…Great improvement (human bone marrow-derived mesenchymal stem cell adhesion, proliferation, and osteochondral differentiation) was observed in this biomimetic graded 3D printed osteochondral construct in vitro. In order to further improve the mechanical performance as well as to add some unique properties (e.g., electron conductivity, thermal conductivity, and biocompatibility), nanofillers are usually added into resin [20][21][22][23].…”

Filtration effects of graphene nanoplatelets in resin infusion processes: Problems and possible solutions

“…To obtain a homogeneous dispersion of GNPs within the epoxy resin, three roll milling (TRM) was used in this work at a constant speed of 200 rpm and progressively reduced gap distance (90/30, 60/20, 45/15, 30/10, and 15/5 µm for back and front gap, respectively), followed by two further dispersion cycles with the parameter of 5 µm back gap distance and 15 N force mode for front gap [18]. Measured amounts of GNPs were added into epoxy resin and dispersed by TRM, while the required amount of hardener was added after TRM processing and prior to the degassing stage.…”

A Photoaddressable Liquid Crystalline Phase Transition in Graphene Oxide Nanocomposites

“…Graphene's exceptional physicochemical characteristics have led to its uptake for a host of composite applications . The intrinsic performance of these materials is mainly dependent on the number of layers forming the graphene derivative and its aspect ratio (e.g., largest lateral dimensions over minimum number of layers), yet the stabilization of single sheet graphene remains challenging and is often poorly compatible with common manufacturing processes, including solvent processing . In contrast, graphene oxide (GO) is mass‐producible and the oxygen moieties that dangle from the basal carbon plane enable aqueous suspensions of high‐aspect ratio GO, with monolayer contents above 95%.…”