ACS NEWS that Bacon may even have produced the first carbon nanotubes without realizing it. The fibers that Bacon discovered possessed an unusually high tensile strength (a measure ofthe amount of force with which a fiber can be pulled before it breaks) and ^bung's modulus (a measure of a material's stiffness—its ability to resist elongation under load). Steel has a tensile strength of 1-2 gigapascals (GPa) and a %ung's modulus of 200 GPa; Bacon's fibers were measured AALOK MEHTA, C&EN WASHINGTON at 20 GPa and 700 GPa, respectively But they were also expensive to make, and even processed high performance carbon yarn, N 1979, ARTHUR c. CLARKE'S NOVEL commercial versions of carbon fibers are "The Fountains of Paradise" popufrom a rayon precursor, was commercialhaunted to this day by high prices. larized the concept of a space elevaized. In 1970, Leonard Singer produced truThe first commercial high-performance tor—one end planted on the equator, ly graphitic fibers, leading to the commercarbon fibers were available by 1963, based the other tethered 40,000 km above cialization of carbon yarn derived from on a process discovered at Parma for heatEarth to a satellite in geosynchronous orliquid crystalline pitch. Carbon fibers are treating rayon. High-modulus fibers bebit—as an efficient way to shuttle materiused in aerospace and sports applications." came available within a few more years, al and people back and forth from space. His fictional engineer solves the structurTHE RESEARCH CENTER in Parma is the when Bacon and Wesley Schalamon used a "hot-stretching" process to stretch caral problems associated with building such 47th site that ACS has designated a Nabon yarn during heat-up, not afterward. an enormous structure by using an ultrational Historic Chemical Landmark since high-strength monofilament carbon fiber. In 1970, Singer made progress on an1992. The landmarks recognize important The space elevator itself remains the other kind of carbon fiber at Parma while places, discoveries, and achievements in stuff of dreams, but high-performance carstudying pitch, a tarlike mixture of hunthe history of chemistry Prior landmarks bon fibers have made it to the final frontier: dreds of branched compounds with difhave included Joseph Priestley's PennsylIn addition to uses in aircraft brakes and fering molecular weights formed by heating vania home, the discovery ofpenicillin, and bodies, lithium batteries, sports equipment, petroleum or coal. He used a "taffy-pulling" the National Institute of Standards & and construction materials, such fibers are apparatus to align molecules in pitch's Technology also vital components of space strucmesophase (its liquid-crystal state) tures and the wingtips of the space and then heated the resulting mixshuttle. The American Chemical Soture to produce a highly oriented ciety designated a key facility in the carbon fiber. development of these fibers, the These graphitized mesophaseUnion Carbide (now GrafTech Inpitch fibers had an even higher ternational) research center in ParYoung's modulus than Bacon's ma, Ohio, as a National Historic fibers (approaching 1,000 GPa) Chemical Landmark on Sept. 17. and showed high thermal conductivity, making them ideal for appliNina I. McClelland, chair of the cations such as brakes and elecACS Board of Directors, presenttronic circuits. ed a plaque to Lionel Batty, director "The Parma Technical Center of corporate research and developmade it possible for scientists like ment at GrafTech, at the event. Roger Bacon and Leonard Singer "The men and women who have to explore the odd, 'funny* results worked at the ParmaTechnical Cen- RECOGNITION McClelland (right) presents a of laboratory experiments," Mcter of Union Carbide transformed plaque honoring the discovery of high-performance Clelland said. 'And the center proour vision of what's possible for carbon fibers to GrafTech's Batty. vided researchers the resources more than two amazingly producthey needed to keep moving forward untive decades," McClelland said. Dan D. Carbon fibers are the artificial equivatil they reached those groundbreaking euEdie, Dow Chemical Professor of Chemilent of spider silk, possessing high stiffreka moments." cal Engineering and director of the Center nesses and tensile strengths that belie their for Advanced Engineering Fibers & Films, Research into carbon fibers continues to low weight. Their discovery is attributed in also spoke. drop their price, opening up new applicalarge part to Bacon, who arrived at Parma tions. Currently used only in small amounts The plaque reads: "Scientists at the Parin 1956 and began carbon arc research, in the automotive industry, less expensive ma Technical Center of Union Carbide studying the melting ofgraphite under high fibers could become the material of choice Corporation (now GrafTech International) temperatures and pressures. for manufacturing entire body panels; they performed pioneering research on carbon Bacon was meticulous: Though he had could also be used in earthquake-proof fibers, for their weight the strongest and produced the first carbon fibers (as graphite homes and bridges. And someday they stiffest material known at the present time. whiskers) in 1958, he didn't publish a paper In 1958, Roger Bacon demonstrated the ulin the Journal of Applied Physics until two might even have a more permanent place in space, linking Earth to the heavens in trahigh strength ofgraphite in filamentary years later, after thoroughly studying his the form of a space elevator. • form. Seven years later continuously find. In the process, some scientists suggest
CARBON FIBER RESEARCH HONORED Site of breakthrough development in Parma, Ohio, is designated a chemical landmark
I
HTTP://WWW.CEN-ONLINE.ORG
C&EN
/ OCTOBER
20. 2003
31
