The World's Longest Carbon Nanotube

Roland Piquepaille writes "As you probably know, carbon nanotubes have very interesting mechanical, electrical and optical properties. The problem, currently, is that they're too small (relatively speaking) to be of much use. Now, researchers at the University of Cincinnati (UC) have developed a process to build extremely long aligned carbon nanotube arrays. They've been able to produce 18-mm-long carbon nanotubes which might be spun into nanofibers. Such electrically conductive fibers could one day replace copper wires. The researchers say their nanofibers could be used for applications such as nanomedicine, aerospace and electronics."

Comments

One more step toward a space elevator?

[SeaDour]

Can these "nanofibers" be used to make a space elevator ribbon? Or does that system require a different method of employing carbon nanotubes?

Re:One more step toward a space elevator?

[camperdave]

Might we not make single-stage-to-orbit vehicles which so drastically reduce the price of launch costs that building a space elevator is not only possible, but unnecessary?

The problem with rockets has never been the mass of the rocket, but the mass of the fuel. There's only so much oomph you can get out of a million litres of hydrogen and oxygen chemically, and it's only marginally more than the power it takes to lift a million litres off the surface and into space. Sure, a lighter fuel tank, and lighter payload will help, but not significantly.

No, if we want cheap access to space, we either go nuclear, or build some sort of space elevator. While we may just be at the threshold of being able to make materials with the tensile strength needed for a beanstalk, we have the tech to make gas core nuclear rockets right now.

Carbon fibre

[TapeCutter]

Apart from more tubes for the interwebs, I would imagine that 18mm is also long enough to make carbon fibre products that are lighter and stronger than what is currently available. I wonder if an America's Cup or F1 winner will one day be built from nanotubes?

Re:Carbon fibre

[evanbd]

Note that nanotubes != CF.

That said, people are already starting to incorporate nanotubes in composite materials. The two hard parts are that they're really slippery and it's hard to get the matrix to stick to them, and that they tend to clump up a lot. The increased length helps with the first problem -- slippery is less of a problem if there's more surface to stick to. I don't know about the dispersion.

Nanotube composites are already impressive. You can get things with 30-50% more stiffness, 50-200% more thermal conductivity, lower thermal expansion, and other useful properties. Metal matrix composites are also impressive. Think aluminum with nanotubes added. You can get double the strength, more than double the stiffness, and double or more the thermal conductivity in something as machinable as aluminum by adding only 1-2% nanotubes. This is a *rapidly* advancing field, and it's poised to seriously change high end materials science in the very near future.

The real killer commercial application

[mad zambian]

will be when someone figures out how to either join these fibres together, or grow a continuous nano-scale monofilament.
Then we will really see what Arthur C was talking about.
The applications for "diamond" fibre are enormous.

Re:Wow

[Reality Master 101]

Ted Stevens actually being prophetic, rather than just wrong.

You know, Stevens gets a totally bad rap on that whole thing. Exactly what is wrong with that analogy? Even UNIX uses the analogy with pipes; Ritchie* could have just easily called them tubes rather than pipes. And yes, the "tubes" of the Internet CAN get clogged up if there's too much flowing through them.

I've never understood why he took such a beating about it. I guess some people are just determined to believe the worst about people, as though the guy though the Internet was literally air-filled tubes.

Re:Wow

[ResidntGeek]

When the tubes of the internet get clogged, it's not because of the tubes, it's because of the machines at the end. When tubes are clogged due to too much toilet paper passing through, you have to dig up the tubes and replace them. When a fiber-optic cable is clogged due to too many movies, you put faster routers at the ends - not at all like digging up a cable network all over the world. That's the problem with the analogy, it broke down *exactly* at the place he invented it for.

Re:Come again

[electrosoccertux]

Just to get some perspective on this, 18mm is about a third of the length of good quality wool fibres.

That puts it in the area of useable length for macro-sized application.

IIRC when Popular Mechanics discussed these nanotubes for building our space elevator, one of the technical hurdles they mentioned was needing nanotubes ~18" in length for the structure to be sound.

Obviously we've got a long ways to go then.

The other thing they mentioned was that given a mathematically perfect carbon nanotube structure, the highest building we could build before it would collapse on itself is something like 90 miles; and we need

Of course both of these are hearsay so take them with a grain of salt, but the important thing I remember is that whatever the max height of a carbon nanotube structure that we could build is, the height required for a space elevator/cable is several orders of magnitude greater.

So why were we funding this stuff again?

Re:Wow

[Burpmaster]

The analogy isn't too terrible. It conveys the notion that Internet bandwidth is a shared resource. However, Ted Stevens demonstrated very clearly that he has no idea what he's talking about. He seems to think that when somebody downloads a movie, the entire movie gets put into the 'tube' and all other data gets in line behind it. He thinks an e-mail he got several days after it was sent arrived late because too many movies were coming through the tubes. Not only that, but he referred to the e-mail as "an internet."

He doesn't realize that data is divided into packets, where a limited amount are in transit at one time for each transfer. This fact is very important. It means that bandwidth is shared roughly evenly between all the users of a 'tube' at any given moment, and that e-mails can always be delivered just a quickly as a few packets of a movie would be delivered. His e-mail could only have been delayed by a messed up mailserver, but he didn't know enough about the Internet to realize that.

Re:Wow

[7Prime]

I'm from Alaska. I fucking hate Ted Stevens, I think he's a jerk, and I disagree with about 95% of his politics. But an idiot he is most definitely not. He knew exactly what he was talking about... which actually worries me a lot more than if he didn't. He was attempting to explain it in layman's terms to a bunch of people, who, honestly, were a lot stupider than him. He has a tendancy to over-dumb-down statements like this.

I think its kinda dangerous to assume that he's stupid, because you fail to realize just how much of a cold, calculating demon he is. Believe me, I know people who used to be former interns of his... they're all hoping he'll die soon, but from what I've heard, his physical health is like that of a 30-year old.

Oh well, as long as his party doesn't get control back, we should be relatively safe.