Carbon fiber is a polymer which is a form of graphite - the gray stuff pencils are made from. Graphite is a form of pure carbon. In graphite the carbon atoms are arranged into big sheets of hexagonal rings. Those sheets look like chicken wire. Actually, that 3-D model of graphite looks a little like an ice cream sandwich! Carbon fiber is a polymer of pure carbon. Oh, of course you figured that out already! Carbon is found naturally in different forms, or arrangements, that really affects its properties. Graphite is a form of pure carbon (another is diamond). The technical term for these different forms of carbon is "allotropes".

In carbon fibers, the carbon is a form of graphite. Graphite is the gray stuff that pencils are made from. (That's right - it's not lead, it's carbon!) In graphite the carbon atoms are arranged into big sheets of hexagonal rings. The sheets look like chicken wire. Actually, that 3-D model of graphite looks a little like an ice cream sandwich! -->

Carbon fiber is a form of graphite in which these sheets are long and thin. You might think of them as ribbons of graphite. Bunches of these ribbons like to pack together to form fibers, hence the name carbon fiber.

These fibers aren't used by themselves. Instead, they're used to make other polymers stronger, like epoxy resins and other thermosetting materials. We call these reinforced materials composites because they are made from more than one material.

Carbon fiber reinforced composites are very strong for their weight. They're often stronger than steel, but a whole lot lighter. Because of this, they can be used to replace metals in many uses, from parts for airplanes and the space shuttle to tennis rackets and golf clubs.

Carbon fiber is actually made from another polymer, called polyacrylonitrile (as shown above) by a complicated heating process.

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