RF heating of carbon nanotubes enables local welding and increased strength between 3D-printed thermoplastic layers.

Electrochemical exfoliation is a promising bulk method for producing graphene from graphite; in this method, an applied voltage drives ionic species to intercalate into graphite where they form gaseous species that expand and exfoliate individual graphene sheets. However, a number of obstacles have prevented this approach from becoming a feasible production route; the disintegration of the graphite electrode as the method progresses is the chief difficulty. Here we show that if graphite powders are contained and compressed within a permeable and expandable containment system, the graphite powders can be continuously intercalated, expanded, and exfoliated to produce graphene. Our data indicate both high yield (65%) and extraordinarily large lateral size (>30 μm) in the as-produced graphene. We also show that this process is scalable and that graphene yield efficiency depends solely on reactor geometry, graphite compression, and electrolyte transport.

Recent developments in the exfoliation, dispersion, and processing of pristine graphene (i.e., non-oxidized graphene) are described. General metrics are outlined that can be used to assess the quality and processability of various "graphene" products, as well as metrics that determine the potential for industrial scale-up. The pristine graphene production process is categorized from a chemical engineering point of view with three key steps: i) pretreatment, ii) exfoliation, and iii) separation. How pristine graphene colloidal stability is distinct from the exfoliation step and is dependent upon graphene interactions with solvents and dispersants are extensively reviewed. Finally, the challenges and opportunities of using pristine graphene as nanofillers in polymer composites, as well as as building blocks for macrostructure assemblies are summarized in the context of large-scale production.

Here, we give the first-ever report of radio frequency (RF) electromagnetic heating of polymer nanocomposite materials via direct-contact and capacitively coupled electric field applicators. Notably, RF heating allows nanocomposite materials to be resistively heated with electric fields. We highlight our novel RF heating technique for multiwalled carbon nanotube (MWCNT) thermoplastic composites and measure their broadband dielectric properties. We also demonstrate three different electric field applicator configurations and discuss their practical use in an industrial setting. We demonstrate the use of RF heating to cure an automotive-grade epoxy loaded with MWCNTs. Our results show that lap shear joints cured faster with the RF method compared with control samples cured in an oven because of the heat-transfer advantages of directly heating the epoxy composite. Finally, we implement our RF curing technique to assemble an automotive structure by locally curing an epoxy adhesive applied to a truck chassis.

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