June 19, 2003
Carbon Nanotube Fibers Tougher, Stronger Than Steel Or Spider Silk

Nanotechnology researchers at the University of Texas at Dallas and at Trinity College in Dublin Ireland have developed nanotube fibers that are stronger and tougher than any known synthetic or natural fiber.

The nanotube threads, created by Ray Baughman and colleagues at the University of Texas, Dallas, and Trinity College, Dublin, have a toughness of 570 Joules per gram. This is three times greater than the toughest natural material, spider silk.

These fibers are 20 times tougher than steel and 17 times tougher than Kevlar.

Now the researchers report they have spun nanotubes into fibers more than 300 feet long; the fibers have the strength of spider silk and more than three times its shock-absorbing toughness. That makes the fibers more than 17 times tougher than the Kevlar used in military flak jackets.

These fibers are both tougher and stronger than steel.

The fibres have twice the stiffness and strength and 20 times the toughness of the same weight and length of steel wire.

The current methods for producing nanotubes still cost many orders of magnitude more than existing materials and the method used to make these fibers is slow and costly as well.

They placed single-walled nanotubes in a rotating bath of aqueous polyvinyl alcohol, yielding gelatinous fibres, which were then coagulated, washed in an acetone bath, dried and reeled up.

This result does far more to demonstrate the performance potential of nanotubes than it does to lower costs. What is most needed to advance the use of nanotubes in materials applications are better methods for making them much more cheaply. While their process may scale well for converting nanotubes to fibers their process does not make the expensive nanotubes that are one of the materials which the process uses.

"We are currently making our fibres on the laboratory scale, producing hundreds of metres of fibre per run," added Baughman. "This basic fibre-spinning process is amenable to upscaling, which will involve increasing the spinning rate and going from single filament to multifilament spinning."

The nanotubes used in these experiments are incredibly expensive.

So far, the biggest hurdle to sewing futuristic nanotube clothes is the $500-per-gram cost of the nanotubes.

The ability of the fibers to function as sensors, electronic circuits, and even energy storage devices creates all sorts of possibilities for unusual clothing.

Or, pushing the envelope of imagination, think of a bulletproof shirt that plays MP3's and receives cellphone calls. (A more realistic potential application would be lightweight body armor that would also provide electrical power for a soldier's radio and other equipment.)

Frankly, I do not see what Kenneth Chang of The New York Times finds so unrealistic about clothing that would play music and take phone calls. Once the costs come down far enough one can easily imagine while people would want to wear clothes that provided so many capabilities. Here's another one: how about embedded temperature sensors that would respond to the change in outside and skin temperature to open and close openings in the cloth to change the level of insulation that one's clothes provide?

These fibers can be used for energy storage.

Baughman and his coworkers have already fashioned the fibers into electricity-storage devices called supercapacitors, which they incorporated into ordinary cloth.

It is likely that the energy storage density of this material is not high enough to get very excited about or they would have more strongly emphasised that part of their results. The discovery of much higher capacity electrical storage materials would enable the widespread use of electric-powered cars and also address the demand for much greater storage capacity for portable electronic devices.

There are many potential uses for incredibly strong textiles.

Baughman and coworkers propose a number of applications for the tough fibrous materials, including safety harnesses and explosion-proof blankets for aircraft cargo areas. In addition, the combination of electronic and mechanical properties may be used to make textiles that serve as sensors, electronic interconnects, and electromagnetic shielding.

Aeorspace, automotive, buildings, bridges, and countless other areas would benefit from much stronger materials. Once nanotubes can be manufactured cheaply they are going to replace existing materials in a large variety of uses and will enable the design of many products that can only be imagined today.

Spacecraft design could be completely revolutionized by advances in nanotechnology. Of course greater strength in materials would allow a reduction in the amount of materials used. But nanomaterials holds out the promise of further weight reduction thru their ability to be structural materials while simultaneously functioning as sensors, electronic circuits, mechanical actuators and other mechanical devices.

Beyond merely being strong, nanotubes will likely be important for another part of the spacecraft weight-loss plan: materials that can serve more than just one function. "We used to build structures that were just dumb, dead-weight holders for active parts such as sensors, processors, and instruments," Marzwell explains. "Now we don't need that. The holder can be an integral, active part of the system."

Imagine that the body of a spacecraft could also store power, removing the need for heavy batteries. Or that surfaces could bend themselves, doing away with separate actuators. Or that circuitry could be embedded directly into the body of the spacecraft. When materials can be designed on the molecular scale, such holistic structures become possible.

Advances in nanotech fabrication techniques will do more to advance the state of the art in aerospace design and manufacture than anything else happening in the aerospace industry today.

Share |      Randall Parker, 2003 June 19 12:07 AM  Materials Advances


Comments
David A. Young said at June 22, 2003 10:42 PM:

While conceding that it's not a near-term application, reading this article caused me to conjecture that this material must be bringing us close to (if not actually surpassing) the material strength needed to make "space elevators" possible. Sufficiently cheap conventional access might undermine the rationale for creating such an economically and technically challenging structure, but DAMN the concept is cool!!

Paul Bloch said at June 29, 2003 6:13 PM:

Well check out www.highlift.com or www.liftport.com for real considerations for space elevators.

Lyman Bishop said at August 27, 2003 9:57 AM:

I am curious if anyone has information concerning what is reffered to as dynamic armor. A system in which carbon nanotubes form a layer of ballistic protection, and are reinforced by the placement of small magnetic particles within the tubes. An electrical charge is then sent through the tubes, which in turn charges the magnetic particles, causing them to attempt to adhere to one another. Thus, reinforcing the armor, and giving it greater ballistic resistance. I read an article some time ago, but I cant seem to find it again. Does anyone have more information?

Eduardo Nocetti Alencar said at November 10, 2004 3:20 AM:

Carbon Nanotube Fiber x Zylon resistance????

Jason Wang said at September 16, 2005 3:29 AM:

Has anyone heard of bacteria or viruses that are encoded by scientists to perform functions, some of which can be mechanical. Which makes possible having a spacecraft designed with those mechanisms, to repair damages, say for instance in the case of traveling at extremely high speeds or space battle?

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