First Pure Nanotube Fibers Made 97
TheSync writes "Researchers at Rice have announced the discovery of how to create continuous fibers from single-wall carbon nanotubes (SWNT). The breakthrough was based on the ability to dissolve a large amount of SWNTs in sulfuric acid, up to 10% SWNTs in solution. At high concentrations, the SWNTs form tightly packed liquid crystals that can be processed into pure fibers. The Space Elevator can't be far away now..."
They don't mention the strength (Score:4, Informative)
Re:Actual strength? (Score:5, Informative)
Wow, that's surprising, considering that Slashdot has had plenty of explanations as to how you do it.
Nanotube strength is more than you need. Much more. Pure carbon nanotube strands are strong enough to make a completely untapered elevator, all by themselves. (300 GPa tensile strength).
For a space elevator, you're not building one continuous nanotube to orbit. That'd be insane. What you do is you build a composite fiber, just like you have fiberglass, or Kevlar fibers - you dope some composite with nanotubes to increase their strength.
Now, you may say "so what? they still have to build them!". They have. Kilometer-long doped CNT fibers have already been produced. No, they're not as strong as you need. Yes, that's being worked on, and yes, it's an engineering problem, not a fundamental flaw. Once you've got kilometer-long length, it's not much more of a step to be thousands of km long (believe it or not). At *absolute worst* you could build a system to join segments of the elevator together. There have already been presentations and ideas on this theory, and it's perfectly sound.
There is nothing fundamental preventing the space elevator from being built. It's just a matter of time, and this is one (very large) step along the way. But it's important to remember that it's just engineering problems - big, but tractable.
Re:Actual strength? (Score:4, Informative)
Nope. That's a theoretical maximum strength; but the theory is probably wrong. Current experimental strength of short fibers is about 120 GPa, and that's only just what you'd need to do this (about 60 GPa is needed, plus a safety factor of say 2).
What you do is you build a composite fiber, just like you have fiberglass, or Kevlar fibers - you dope some composite with nanotubes to increase their strength.
Not quite. If you dope a plastic with nanotubes you'd end up with a material whose strength and weight were dominated by the polymer. That would be wayyyy too heavy and weak. The idea is that you have to use an absolute bare minimum of glue to stick the nanotubes fibers together. Trouble is no-one knows how to do this right now with adequate strength; nanotubes are slippery and particularly hard to glue; and as noted, we don't have a great deal of strength to play with- we need a safety factor for practical reasons.
Kilometer-long doped CNT fibers have already been produced. No, they're not as strong as you need. Yes, that's being worked on, and yes, it's an engineering problem, not a fundamental flaw.
Those fibers aren't even as strong as Kevlar. So, no, it's still a research problem. The engineering begins when we have a cable even a few feet long; of the right strength/weight ratio. Until then- engineers and financiers must hang fire.
Technical data on Space Elevator (Score:4, Informative)
Institute for Advanced Concepts [usra.edu]
and here is a design study for a space elevator:
Space Elevator Phase 1 [usra.edu]
Space Elevator Phase 2 [usra.edu]
Nanotubes are sticky (Score:5, Informative)
The process they describe here is a way of storing the nanotubes for transport, so that they can be assembled later.
Creating nanotubes is dead-on easy. I've actually seen a nanotube creation lab in the Physics department in the University of Washington. I think it is on the third or fourth floor. Go visit there if you get a chance.
After the nanotubes are created, they have to be seperated. They come in a hairball and need to be seperated individually. Next they are stored in a liquid type suspension. When they want to form their nanotube rope, they need a way to squeeze them back together again and extract all of the liquid. The liquid described in the article is beneficial because it helps organize the nanotubes so that they can be easily extracted. You will end up with 100% pure nanotube rope or cable at the end of the process.
Now you are probably speculating that it can't be that simple. It is. Sheep hair (wool), cotton fiber, polyester, and such all work in the same way.
Space elevator news/portal (Score:2, Informative)
I'm glad to see so many space elevator stories on Slashdot lately. I think the actual feasibility of this idea is important to impress upon people. SE research has a considerable amount of NASA funding, the fruits of which where the Phase I & II NIAC reports mentioned in the parent post.
LiftWatch.org [liftwatch.org] is a news/portal site dedicated to following this and other developments in space elevators and related technologies. Besides the main front page news, here are some handy links for the SE afficianado:
I've been trying to get Slashdot to add LiftWatch headlines as an RSS feed. If you find the site interesting, please let the /. editors know so that there can be a LiftWatch.org slashbox.
Re:Invisbly cut someones throat (Score:2, Informative)
Wiliam Gibson, "Johhny Mnemonic"? IIRC, it features a japanese dude with a 'monomolecule' spooled in his thumb, used for exactly that purposes.
Re:just the space elevator? (Score:3, Informative)
I would suspect fullerines have similar conductance to graphite
Plus, a previous slashdot story indicated that fullerines undergo total disentegration under some conditions [slashdot.org]
Nanotubes as transistors [slashdot.org]
NAnotubes extend battery life [slashdot.org]