modern era of carbon fibers began in 1956, when Union Carbide opened its
Parma Technical Center just outside Cleveland. The complex was one of
the major laboratories of Union Carbide’s basic research program,
modeled after the university-style corporate labs that became popular
in the late 40s and 50s. They gathered young, bright scientists from a
variety of backgrounds and let them loose on their favorite projects,
giving them an extraordinary degree of autonomy.
With a freshly minted Ph.D. in physics, Roger Bacon joined the Parma staff
in 1956. “I got into carbon arc work, studying the melting of graphite
under high temperature and pressures,” Bacon recalls. “I took
on the job of trying to determine the triple point of graphite. That’s
where the liquid, solid, and gas are all in thermal equilibrium.”
The equipment was akin to the early carbon arc streetlamps, only operating
at much higher pressures. Small amounts of vaporized carbon would travel
across the arc and then deposit as liquid. As Bacon decreased the pressure
in the arc, he noticed that the carbon would go straight from the vapor
phase to the solid phase, forming a stalagmite-like deposit on the lower
electrode. “I would examine these deposits, and when I broke one
open to look at the structure, I found all these whiskers,” he says.
“They were imbedded like straws in brick. They were up to an inch
long, and they had amazing properties. They were only a tenth of the diameter
of a human hair, but you could bend them and kink them and they weren’t
brittle. They were long filaments of perfect graphite.”
The year was 1958, and Bacon had demonstrated the first high performance
carbon fibers. In fibrous forms, carbon and graphite are the strongest
and stiffest materials for their weight that have ever been produced.
Bacon demonstrated fibers with a tensile strength of 20 Gigapascals (GPa)
and Young’s modulus of 700 GPa. Tensile strength measures the amount
of force with which a fiber can be pulled before it breaks; Young’s
modulus is a measure of a material’s stiffness, or its ability to
resist elongation under load. For comparison, steel commonly has a tensile
strength of 1-2 GPa and Young’s modulus of 200 GPa.
Carbon fibers are polymers of graphite, a pure form of carbon where the
atoms are arranged in big sheets of hexagonal rings that look like chicken
wire. Bacon’s graphite whiskers were sheets of graphite rolled into
scrolls, with the graphite sheets continuous over the entire length of
“After studying the heck out of these things, I finally published
a paper in the Journal of Applied Physics in 1960,” Bacon
says. The paper has since become a milestone, partially because some have
claimed that Bacon may have been the first person to produce carbon nanotubes
— hollow cylinders of graphite with diameters on the order of single
molecules. Their incredible properties have made nanotubes one of the
hottest areas of research in recent years, promising to revolutionize
just about every area of science. Sumio Iijima published a paper in 1991
that is often regarded as the first discovery of carbon nanotubes; it
reported on a method that produced both tubes and scrolls. The process
is similar to Bacon’s, suggesting that he too may have prepared
nanotubes along with his whiskers, although he didn’t know it at
the time. “I may have made nanotubes, but I didn’t
discover them,” he says.
By producing his high strength and high modulus whiskers, Bacon had demonstrated
experimentally something that theoreticians had proposed long ago. But
the fibers were still just a laboratory phenomenon, not a practical development.
“I estimated the cost of what it took to make them, and it was $10
million per pound,” he says. To tap their full potential, manufacturers
needed a cheap and efficient way to produce the fibers. Much of the research
in the ensuing decades was dedicated to exactly that.