Carbon is undoubtedly the most important chemical element on Earth. It is the element of life, the source of most of the world’s energy, the basis of plastics, and the major industrial pollutant in the atmosphere.
Carbon has properties that make it the ideal chemical for life, the ultimate source of fossil fuels, but its role extends far beyond its importance as a biochemical.
As we aim for a decrease in carbon dependency for energy, this versatile chemical element will have many diverse and greener roles in the future.
New technology under development now allows plastic production from captured methane, a major greenhouse gas.
The utility of the carbon atom is due to its four electrons. These "valence" electrons are free to bond with other atoms, including other carbon atoms. This is what makes it possible for the long chains in the molecules of life and the hydrocarbons in fuel and plastics.
Diamond and graphite are both crystalline forms of carbon-to-carbon bonds, the only difference being the arrangement of carbon atoms in the crystal lattice.
Diamonds are hard because the interlocking lattice of bonded carbon atoms makes a strong structure.
Graphite is slippery because it consists of thin sheets of bonded carbon atoms. The bonds between carbon atoms are strong as in the diamond lattice, but the bonds between the sheets are weak, allowing the layers to slide over one another.
The strength of graphite sheets has led to the development of composite materials made from carbon fiber impregnated with resin similar to the way Fiberglas cloth and resin are used.
The difference is that the carbon fibers are 100 times stronger than steel but weigh only one-sixth as much.
Most carbon fibers are made from a rayonlike material, polyacrylonitrile. Others are made from rayon, nylon or petroleum pitch. The exact composition of precursor materials varies among companies and is generally proprietary.
Each fiber consists of narrow sheets of graphite that roll up and join at the end to form interlocking hollow tubes that are one-tenth the thickness of a human hair.
Carbon fiber composites are used to make aircraft and spacecraft parts, racing car bodies, golf club shafts, tennis rackets, bicycle frames, fishing rods, automobile springs, sailboat masts, musical instruments and blades for huge industrial wind generators, to name a few.
The most dramatic and revolutionary use of carbon fiber technology is in the Boeing 787 Dreamliner.
The fuselage and wings of the Dreamliner are made from carbon fiber composite, making the airframe much lighter than if it were made of aluminum or titanium.
With lighter weight and fuel-efficient engines, the innovations of the 787 will save millions of dollars over the life of the aircraft.
It also provides greater comfort for passengers. The stronger airframe allows the cabin pressure to be maintained at a higher level, and the noncorrosive composite will allow for higher humidity in the cabin.
Despite early problems with its onboard batteries, the Dreamliner is one of many innovations that the 21st century will see from the use of carbon and carbon fibers.
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Richard Brill is a professor of science at Honolulu Community College. His column runs on the first and third Fridays of the month. Email questions and comments to brill@hawaii.edu.
