Rensselaer Research Review Spring/Summer 2010
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* Graphene Is Potential Key to Next Generation Nanocomposite Materials

New studies by Professor Nikhil Koratkar show graphene outperforms carbon nanotubes and other nanoparticles for boosting the strength and mechanical performance of epoxy composites. Pictured are graphene platelets that Koratkar's research team extracted from bulk graphite.

Study Shows Graphene Could Help Prevent Fracture and Fatigue Failure in Composite-Based Structures Including Windmill Blades and Aircraft Wings

Koratkar said graphene has three distinct advantages over carbon nanotubes. The first advantage is the rough and wrinkled surface texture of graphene, caused by a very high density of surface defects. These defects are a result of the thermal exfoliation process that the Rensselaer research team used to manufacture bulk quantities of graphene from graphite. These “wrinkly” surfaces interlock extremely well with the surrounding polymer material, helping to boost the interfacial load transfer between graphene and the host material.

The second advantage is surface area. As a planer sheet, graphene benefits from considerably more contact with the polymer material than the tube-shaped carbon nanotubes. This is because the polymer chains are unable to enter the interior of the nanotubes, but both the top and bottom surfaces of the graphene sheet can be in close contact with the polymer matrix. 

The third benefit is geometry. When microcracks in the composite structure encounter a two-dimensional graphene sheet, they are deflected, or forced to tilt and twist around the sheet. This process helps to absorb the energy that is responsible for propagating the crack. Crack deflection processes are far more effective for two-dimensional sheets with a high aspect ratio such as graphene, as compared to one-dimensional nanotubes.

Koratkar said the aerospace and wind power industries are seeking new materials with which to design stronger, longer-lived rotor and wind turbine blades. His research group plans to further investigate how graphene can benefit this goal. Graphene shows great promise for this because it can be produced from graphite, which is available in bulk quantities and at relatively low cost, he said, which means mass production of graphene is likely to be far more cost effective than nanotubes.

Co-authors on the three papers include Rensselaer mechanical engineering graduate students Mohammad A. Rafiee, Javad Rafiee, and Iti Srivastava; as along with Professor Zhong-Zhen Yu’s group at the Beijing University of Chemical Technology.

Koratkar’s research is funded by the U.S. Office of Naval Research (ONR), U.S. Army, and the U.S. National Science Foundation (NSF).

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