Graphene

Graphene itself is generating great deal of excitement. It is actually a single layer of graphitic carbon, and being only one atom thick is a true two-dimensional material.

(It is worth noting that, as such, it is under the minimum size of 1 nm in the nano definition.) Graphene is also the fundamental unit of nano carbon fibers and carbon nanotubes.

The interest in this material stems from its strength and stiffness, which are put at 130 GPa and 1 TPa (terra Pascal), respectively. It is said to be the strongest material currently known. From a composites point of view, it has the potential for very strong and stiff but light composite materials (its effective specific gravity is 2.25). While graphene was known theoretically for many years, it was only recently that an effective method of producing these single layers was discovered (Novoselov et al. 2004). This involved the mechanical removal of single atomic layers from graphite. This work resulted in the award of the Nobel Prize for Physics in 2010. Better methods were required for scale up and commercial exploitation, and over time a number of alternatives have been developed. These have been reviewed by Soldano et al. (2010). The approaches being investigated include chemical vapor deposition, graphitization of silicon carbide, a large variety of graphite exfoliation methods (including the ultrasonic method of the Drzal group described above), unzipping of carbon nanotubes, and chemical synthesis.

Enormous effort is going on worldwide to develop commercially affordable methods of production and to find applications for graphene and its composites. These efforts are expected to start to come to fruition in the next few years. Even so, there are significant issues in being able to produce graphene in a form suitable for use as a plate in composites manufacture though. Not least is its desire to roll up into a tube or to form buckled or crumpled plates. It may be that the use of stacks of a few sheets, as described under graphite above, may be more practical for composites.

 
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