Exfoliated Graphite Nanoplatelets (xGnP): A Carbon Nanotube Alternative
L.T. Drzal and H. Fukushima
Michigan State University, US
Nanocomposites are opening up ‘windows of opportunity’ for new applications of polymers to not only structural but also non structural areas by providing ways to tailor surface, electrical, thermal and barrier properties. The choices of carbon-based nanoreinforcements are growing ranging from single walled carbon nanotubes (SWNT), multi-wall carbon nanotubes (MWNT), carbon nanofibers (CNF) and fullerenes (buckyballs) as well as nanoclays and cellulose nanowhiskers. These materials are considered to be some of the main materials to be used in wide range of industries in the future because of their superiority in many aspects, including mechanical, electrical, thermal, and storage properties. The possible applications include nanocomposites, batteries, fuel cells, fuel storage, etc. Nanocomposites are considered to be one of the main applications, but the biggest drawback is the high cost and their limited availability. Since the late 1990’s, research has been underway in our group at MSU to investigate the fabrication of new nano-size carbon material, exfoliated graphite nanoplatelets [xGnP]. The xGnP is fabricated from natural graphite and can be used as a nanoreinforcement for polymers as an alternative to expensive carbon-based nanomaterials. Since graphite is the stiffest material found in nature having a modulus several times that of clay, accompanied with excellent strength, electrical and thermal conductivity, an exfoliated nanoplatelet should have similar properties to carbon-based nanomaterials. In this research, natural crystalline graphite based graphite intercalated compounds [GICs] were exfoliated into xGnP. TEM images and showed the average thickness of the xGnP became 5-10nm range. BET data showed the surface area of the xGnP reached more than 100m2/g. SEM images confirmed that the size of the xGnP can be controlled from sub-micron level to few hundred um. The cost of producing this new nano-size graphite material was estimated to be around $5/lb or less. Micromechanics principles will be used to exploring what can be gained by the use of nanocomposites and the properties that can be modified from primarily a mechanical viewpoint. Numerous examples of mechanical, thermal, electrical and barrier properties from polymer systems (both thermoset and thermoplastic) systems will be presented to illustrate the potential of these platelet nanomaterials. The results will be compared and contrasted with the same polymer matrices reinforced with conventional reinforcements such as carbon fibers, glass fiber, vapor grown carbon fibers and particulate fillers.
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Nanotech 2006 Conference Program Abstract