Rensselaer Research Review Spring/Summer 2010
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Exploring the Properties of Next Generation Nanaocomposites
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Recent studies involving Nikhil Koratkar, professor in the Department of Mechanical, Aerospace, and Nuclear Engineering at Rensselaer, have furthered our understanding of next-generation nanocomposites. One area of research explored the special mechancial properties of composites infused with graphene. Other research involves the development of new coatings for nanosensors that could lead to more accurate and efficient oil exploration.

Graphene Outperforms Carbon Nanotubes for Creating Stronger, More Crack-Resistant Materials

Composites infused with graphene are stronger, stiffer, and less prone to failure than composites infused with carbon nanotubes or other nanoparticles, according to three new studies. This means graphene, an atom-thick sheet of carbon atoms arranged like a nanoscale chain-link fence, could be a key enabler in the development of next-generation nanocomposite materials.

“I’ve been working in nanocomposites for 10 years, and graphene is the best one I’ve ever seen in terms of mechanical properties,” said Koratkar, who led three recent studies. “Graphene is far superior to carbon nanotubes or any other known nanofiller in transferring its exceptional strength and mechanical properties to a host material.”

Results of Koratkar’s studies are detailed in three recently published papers: “Fracture and Fatigue in Graphene Nanocomposites,” published in Small; “Enhanced Mechanical Properties of Nanocomposites at Low Graphene Content,” published in ACS Nano; and “Buckling Resistant Graphene Nanocomposites,” published in the journal Applied Physics Letters.

Advanced composites are increasingly a key component in the design of new windmill blades, aircraft, and other applications requiring ultra-light, high-strength materials. Epoxy composite materials are extremely lightweight, but can be brittle and prone to fracture. Koratkar’s team has infused the advanced composites with stacks, or platelets, of graphene. Each stack is only a few nanometers thick. The research team also infused epoxy composites with carbon nanotubes.

Epoxy materials infused with graphene exhibited far superior performance

Epoxy materials infused with graphene exhibited far superior performance. In fact, adding graphene equal to 0.1 percent of the weight of the composite boosted the strength and the stiffness of the material to the same degree as adding carbon nanotubes equal to 1 percent of the weight of the composite. This gain, on the measure of one order of magnitude, highlights the promise of graphene, Koratkar said. The graphene fillers also boosted the composite’s resistance to fatigue crack propagation by nearly two orders of magnitude, compared to the baseline epoxy material.

Though graphene and carbon nanotubes are nearly identical in their chemical makeup and mechanical properties, graphene is far better than carbon nanotubes at lending its attributes to a material with which it’s mixed.

“Nanotubes are incredibly strong, but they’re of little use mechanically if they don’t transfer their properties to the composite,” Koratkar said. “A chain is only as strong as its weakest link, and if that link is between the nanotube and the polymer, then that is what determines the overall mechanical properties. It doesn’t matter if the nanotubes are super strong or super stiff, if the interface with the polymer is weak, that interface is going to fail.”

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“Exploring the Properities of Next-Generation
Nanocomposite Materials ”
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