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

Wow

[jswigart]

So perhaps the internet will indeed become a series of tubes?

Re:Wow

[Jeff DeMaagd]

Maybe. Maybe in an odd twist, the Internet might actually become a large fleet of nano-trucks.

Re:Wow

[ScrewMaster]

That's a scary thought ... Ted Stevens actually being prophetic, rather than just wrong.

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

[espressojim]

Maybe this is why? Even if the metaphor isn't horrible, the delivery was:

Ten movies streaming across that, that Internet, and what happens to your own personal Internet? I just the other day got... an Internet was sent by my staff at 10 o'clock in the morning on Friday, I got it yesterday. Why? Because it got tangled up with all these things going on the Internet commercially.

[...] They want to deliver vast amounts of information over the Internet. And again, the Internet is not something you just dump something on. It's not a big truck. It's a series of tubes. And if you don't understand those tubes can be filled and if they are filled, when you put your message in, it gets in line and it's going to be delayed by anyone that puts into that tube enormous amounts of material, enormous amounts of material.

From wikipedia.

Re:Wow

[Anonymous Coward]

Exactly what is wrong with that analogy?

The context it was said in, he did not say "The Internet is a worldwide, publicly accessible network of interconnected computer networks that transmit data by packet switching using the standard Internet Protocol (IP) [Wikipedia]... You can think of it as a series of tubes...".

Here's a clip with interesting parts from his speech.

I'm also sure you can find the whole thing in the related clips pane. Listen to it (again?) and judge for yourself if he knows what he's talking about

I've never understood why he took such a beating about it

I believe the beating was NOT because he doesn't understand "what the internet is" (that's not a crime, last time I checked), but the fact that he's a legislator working on something that he does not understand at all.

And of course this generation likes bashing on older people because they don't know that the next generation will mock them just the same...

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: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.

Re:Wow

[hey!]

The proof of the pudding is in the eating.

The proof of the analogy is in the reasoning. Senator Stevens, if you recall, was blaming net neutrality for the fact that his email sent by one of his staff on Friday morning didn't arrive in his inbox until the following Sunday morning.

So, yes, I think Senator Stevens deserves a round of jeers on this one. He's obviously bought a load of tosh about how net neutrality hurts users.

In any case, the correct analogy would be: "The Internet is a NETWORK of tubes." This would lead to more correct reasoning. Since the Internet is a network of tubes, if one tube is blocked up, then stuff just flows through a different path. If email don't make it to me in time, it's because there is a screwup at an end point in the network, since blockages in the middle don't delay things much, if at all. This means I should talk to the persons who manage my email server or who manage the specific tube that links that server to the broader network of tubes.

One nanotube: two birds

[ian_mackereth]

So, not only will we get light, cheap, immensely strong conductors, we'll also have a good market-driven reason to get all that valuable carbon out of the atmosphere!

Voila! No more global warming!

8-)}

Come again

[Anonymous Coward]

"Extremely long"?

Perhaps 18 mm stands for... 18 million miles?

Re:Come again

[Anonymous Coward]

Perhaps 18 mm stands for... 18 million miles?

18mm is extremely long for most nerds

Re:Come again

[ian_mackereth]

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.

Re:Come again

[evanbd]

Well, they're still more slippery than wool, so that problem has to be solved too. But this is one piece of the puzzle, and it's very cool to see it coming along.

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:Come again

[gringer]

you misspelt "pond"

Re:Come again

[dcmeserve]

given a mathematically perfect carbon nanotube structure, the highest building we could build before it would collapse on itself is something like 90 miles... ..the height required for a space elevator/cable is several orders of magnitude greater

Carbon nanotubes have their strength in tension, not compression.

A self-supporting building based on nanotubes would have to be a tensegrity structure of some kind, where you'd have nanotubes pulling against something else that's relatively incompressible; maybe a diamond lattice. The tensions involved at the base of such a structure would be immense to keep the thing rigid enough to remain standing.

A space elevator, on the other hand, would rely purely on tension; the centrifugal effects of following the Earth's rotation are what keep it aloft -- that's the beauty of it. The tension forces -- greatest just below the geostationary orbit height -- would be large, but perhaps not as large as in the tensegrity structure.

So why were we funding this stuff again?

You call this funding?

As Mork would say...

[sycodon]

Nano nano nano.

ZOMG BOYKOTT R0L4ND!1!

[pestie]

Did I get it right in the subject line? Apparently all Slashdotters are supposed to hate this Roland guy, right? God, I just want so desperately to be loved...

Re:ZOMG BOYKOTT R0L4ND!1!

[ColaMan]

While I don't condone his actions in the past (that is, using /. to push more views to his site for personal gain), he doesn't link-through his site anymore. So now, he's just another submitter of crappy stories that generally give off wildly over-optimistic expectations of future possibilities.

That's what she said

[Syberghost]

(eom)

Re:Now where s my space elevator?

[Anonymous Coward]

18mm? Can be spun together into longer fibers? Get me to space.

Forget space. I just want my flying car they promised me ten years ago.

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?

[QuantumG]

Two points I like to make about the space elevator:

This isn't tomorrow's technology, it is something the human race might do a hundred years from now.

If we have the super strong, super light materials needed to make the space elevator, what else might we do with them? Might we not make better rockets? Or better planes? 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?

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.

Re:One more step toward a space elevator?

[evanbd]

It's not about the fuel prices. Never has been, and won't be for the foreseeable future. Propellant is cheap, it's the vehicle that's expensive. Elon Musk of SpaceX was recently quoted as saying propellant costs are comparable to the accounting errors.

Remember that the space elevator has to supply all the energy to the payload too, but it has to get it in a much more expensive form -- like electricity beamed from the ground by lasers or some such. Rockets aren't actually all that energy inefficient in comparison.

I used to be a huge fan of the space elevator idea, but then I started looking what those same materials do to rockets. SSTO is just the start. And remember, those materials will change rockets long before they make a space elevator.

Of course, I am a rocket engineer, so I might be a little biased, but I've also examined the problem in some detail :)

Re:One more step toward a space elevator?

[evanbd]

People don't seem to get this somehow. Yes, mass ratio matters. A lot. Let's look at LOX+Kerosene, a very typical combination in many ways. You get an ISP of about 3000 m/s in a medium-high performance vacuum engine (the case for most of the way to orbit). LEO takes about 9000 m/s of delta-v by the time you account for aerodynamic and gravity losses. That means the mass ratio of your rocket needs to be about e^(9000/3000) = e^3 = 20. So 5% of your rocket makes it to orbit. Yup, that sucks. LOX costs about $0.07/lb in bulk, kerosene about $0.30. So propellant costs are about $0.15/lb for propellant, or $3/lb of orbited mass.

Now lets look at the space elevator. Climbing to geosynchronous orbit is equivalent to about 8000 m/s of delta-v (roughly... don't have the exact number off hand and I don't feel like calculating it). From 1/2M*v^2, that's 32MJ/kg. That's about the energy you get from burning 6 kg of LOX-kerosene. So from an energy equivalence standpoint, you're using 6 kg of propellant worth of energy instead of 19 -- a factor of 3 improvement.

The problem with the space elevator is twofold. First, the required *form* of the energy is different. You can't just use cheap hydrocarbon fuels -- you have to convert it to electricity, and then get that electricity up to the elevator either by beaming it or along wires, and neither option is efficient in the slightest. In fact, by the time you turn the hydrocarbon fuel into electricity and then get it to the elevator car, you're under 50% efficient; being as high as 30% would take a lot of work and be quite impressive. But the rocket was 30% efficient! Space elevators are *not* particularly more efficient than rockets.

The second problem is the infrastructure of the space elevator -- the required capital investment for a certain payload rate (kg delivered per day) is higher than for the rocket (we won't even discuss non-reusable rockets). Even if you got the space elevator more energy-efficient than the rocket, this fact combined with the slower transit time, the geosynchronous orbit as the only one available, and the more complicated technological requirements, the rockets win.

Yes, the space elevator tech is harder. The ribbon itself and the beamed power are the obvious examples, but there are others. For example, the tires on the car that work against the ribbon -- you need tires that run at about Mach 3 and are good for 27000 miles. That's not even remotely easy. You need motors that have higher power to weight ratios than currently exist. Etc, etc, etc. Rockets, in comparison, are easy. Especially if you have space-elevator class building materials available -- at that point you can do SSTO with pressure fed rockets, and get rid of the pumps altogether -- the pumps being the hardest part of rocket engine development by far in a conventional design.

When people say that for space elevators you only have to provide the energy to climb up, and aren't wasting the energy carrying propellant, they often forget that it's actually a *lot* of energy to climb up, and that rockets are actually remarkably good at converting available chemical energy into exhaust kinetic energy -- some are better than 80% efficient by that metric.

Re:One more step toward a space elevator?

[Ash Vince]

Your idea of a space elevator is interesting, but very wasteful.

To make a far more energy efficient design you need to run the cars at constant speed. You also need to attach each car together. That way you can use the energy of the cars on the way down to help power the cars on the way up, much more like how a real elevator works. This means that the whole system requires a much more constant energy input.

This also does away with the idea that each car ever stops. It presents a problem of how you load and unload a moving system at the bottom but this is certainly a solvable problem. At the top you just have a fleet of small craft who dock with each car. Everything is moving in space anyway so all you need to do is match velocities, something the shuttle already does with the space station.

The mistake you seem to be making is trying to treat each car as separate entity rather than looking at the system as a whole. If you can do this then you can use the potential energy of the stuff (raw materials, people coming home, etc) you are bringing back rather than wasting it. This is why space elevators have the capability to be far more energy efficient than rockets ever can.

Now before everyone replies with all the problems, I know, its hard. The fact remains however that continuing on the current task of using semi reusable rockets (like the shuttle and it SRB's) then just letting the stuff we want to bring back fall is not an option. It wastes too much energy from the standpoint of bringing materials back.

Once I could have filled my post with numbers too, but I finished Physics (with Space Tech) several years ago now and have forgotten most of the maths needed.

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.

18 mm... Great!

[camperdave]

18 millimetres? Great, only 99,999.999982 km to go!

My microtube is bigger than your nanotube

[mrbluze]

... do you think they could be compensating for something?

Great...

[DoofusOfDeath]

Now we're going to get spam advertising ways to lengthen our nanotubes...

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.

some perspective

[Goldsmith]

Although the PR person who wrote this obviously thinks this is a major breakthrough, these guys are using a method which was originally invented by Japanese researchers three years ago (google for "CNT super growth"). The Japanese guys have since focused on getting the fastest growth rate possible (I think it's about 0.2mm/min... if you want to figure out how many, many years it would take to grow a space elevator). There are lots of people working on improving this growth method, 18mm arrays may be the longest, but it seems to be in the same range as other people working on the "super growth" method. That doesn't diminish this research, rather it means that this method is very likely to work in the long run for industrial scale growth of nanotubes for materials (more simply, it's easily reproducible, and people want "nano-enhanced" golf clubs).

Isolated nanotubes have been grown longer than this (I've grown isolated nanotubes longer than this, and I'm not a growth specialist), as have bundles of nanotubes. This is the longest array of pure, aligned, continuous nanotubes.

Re:Now where s my space elevator?

[confused one]

It's quite a stretch to go from 18mm to geo-sync orbit, isn't it?!

RTFA

[Raynor]

It would be nice if people actually read up the subject before posting this garbage...

This is not "The World's Longest Carbon Nanotubes." It's the longest mass-producable parallel carbon nanotubes.