Saturday, June 30, 2012

Graphene, Nanotubes and Carbon Fiber

Carbon Super-Materials Will Change the World

Posted by Tom Hartsfield on RealClearScience at Wed, 27 Jun 2012

During the early 20th century there was a revolution in the materials used everywhere around us due to the inventions of polymer chemistry. Polymer molecules are long chains--only a few atoms wide but many, many atoms long--bonded covalently. (They share their outermost electrons, which is generally the strongest way atoms can bond together.)

Nylon, vinyl, polyethylene (plastic bags and sheets), mass-producible polystyrene (Styrofoam), polypropylene (plastic containers and furniture), Teflon, PVC, etc. Pretty much everything cheap that we buy and use every day was invented in a chemistry lab.

Starting in the late 20th century and taking off particularly over the past two decades, a potentially similar revolution in materials has been brewing. This time it is due to the chemical properties of carbon. Carbon is able to form extremely strong bonds with other carbon atoms.

All-carbon structures come in many forms, and three currently stand out. Sheets of carbon atoms, called graphene; hollow tubes of rolled up graphene, called nanotubes; and carbon fiber, made of stacked sheets of graphene. Each of these three extraordinary materials deserves its own story. Considered as a class, they may well similarly change what we make things out of, and, subsequently, what those things are capable of doing.

Graphene might be the best material in the world for conducting heat and electricity. A sheet of pure graphene the size of a piece of cling wrap could support a car balanced on a pencil on top of it. Right now, it is too expensive to find much commercial use, but its price has dropped enormously over the past few years and will probably continue to do so.

Carbon nanotubes, which are simply graphene sheets rolled into a tube, inherit many of the same properties. They can be used to make super-strong materials and conductors as well. Japan wants to use them to build a space elevator.

Finally, the material that is already starting to change the world is carbon fiber. It is nearly ubiquitous in applications where low weight for a certain strength is highly desirable (and worth paying for). Lance Armstrong rides entirely carbon-fiber bicycles. Major auto manufacturers are beginning to use it to build car body parts, and carbon-fiber prosthetic legs are so amazing that they may be unfair for sprinters to use in the Olympics.

Beyond luxury sporting goods however, carbon fiber is beginning to become cheap enough to find other uses. Furniture, musical instruments, solar cells, scientific equipment, bridges--once the price falls low enough, nearly any structural application can be improved dramatically with carbon-fiber and other carbon materials.

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