Nanotubes Start to Show their Promise 329
Rei writes "Researchers at the University of Texas at Dallas have developed the highest quality nanotube sheets to date (the team previously set strength records with polymer-nanotube composites). Producable at a rate comparable to commercial wool spinning, the transparent cloth has exceedingly high conductivity, flexibility, has huge surface area to volume ratios, can potentially be made into very effective OLEDs and thin-film photovoltaic cells, and outperforms even our best bulk materials (such as Mylar and Kevlar) at strength normalized to weight. It strongly absorbs microwaves for localized heating (leading to applications in seamless microwave welding of sections and even windshield warming), changes conductivity little over a wide temperature range (very useful in sensors), and is expected to be used in commercial applications very soon. The research should even be expandable to artificial muscles! To head people off, while the exact tensile strength is not listed, it sounds like it is still far from the >100 GPa needed for a space elevator. Anyways, here's to process advancements!"
Producable at a rate... (Score:5, Informative)
Unfortunate about the space elevator. Looks like the highest we've gone is 63 GPa (http://en.wikipedia.org/wiki/Tensile_strength [wikipedia.org])
Re:Cost is irrelevant (Score:5, Informative)
Why they are weaker (Score:5, Informative)
In this case, when they are weaving fibers together, the weakness in tensile strength will come from the interface between linked nanotubes which will have a tensile strength many orders of magnitude than that of an individual tube.
Re:Space elevators (Score:1, Informative)
Baby steps.
Funny... (Score:2, Informative)
Dallas Morning News - Article and Video (Score:2, Informative)
Article URL: http://www.dallasnews.com/sharedcontent/dws/dn/lat estnews/stories/081905dnmetnanosheet.1c9439ac.html [dallasnews.com]
Video URL: http://www.dallasnews.com/s/dws/spe/2005/nanotech/ [dallasnews.com]
---------
LITTLE CREATION, BIG STEP
UTD team's chemical ribbons could assist many high-tech dreams
09:01 PM CDT on Thursday, August 18, 2005
By SUE GOETINCK AMBROSE / The Dallas Morning News
Scientists from the University of Texas at Dallas have spun yards of chemical ribbons that are lighter than a feather but stronger than steel a significant advance in the rapidly growing field of nanotechnology.
(Picture: LOUIS DeLUCA/DMN University of Texas at Dallas scientists (from left) Mei Zhang, Sergey Lee, Ali Aliev, Anvar Zakhidov, Shaoli Fang and leader Ray Baughman took part in the research.)
The development could lead to a host of high-tech applications that scientists have dreamed of but haven't had an easy way to create: futuristic clothes that light up, store energy or blunt bullets; car doors that are ultra light, extra strong and double as batteries to store solar energy; flexible, filmy light bulbs that are thinner than a human hair; artificial muscles for robots; and solar sails to propel space vehicles.
A report describing the chemical ribbons, created from tiny carbon tubes barely visible to the human eye, appears in Friday's issue of the journal Science.
"This is a big deal, a real big deal," said James Tour, a chemist at Rice University in Houston, of the new study. "Every paragraph is a gold mine."
The ribbons are created from carbon nanotubes, filaments about one-five-thousandth the width of a human hair. At the atomic level, the nanotubes look like cylinders of chicken wire. Because the nanotubes, like diamonds, are made entirely of carbon, they are extraordinarily strong. They also conduct electricity.
Scientists had known of carbon nanotubes' exceptional properties but had struggled to easily convert them into convenient forms. Last year, the UTD scientists, led by chemist Ray Baughman, had spun the nanotubes into yarn. Other scientists had created small sheets of nanotubes, but their process was cumbersome. DallasNews.com/extra
"The value of this invention is to make it into sheets," said Ned Thomas, a materials scientist at the Institute for Soldier Nanotechnologies at the Massachusetts Institute of Technology in Cambridge. "Clever people will take those sheets and put them into technologies that have yet to be invented."
THE PROCEDURE
Making the ribbons is quite simple, Dr. Baughman said. The UTD scientists started with a "forest" of nanotube trees, about one-third of a millimeter high. Then they stuck a Post-It note to one edge of the forest and gently pulled away. The nanotube trees were drawn out, and as the researchers kept pulling, the trees stuck to each other side by side, forming a long, wispy and transparent sheet.
Sheets more than a meter long, about two inches wide, and less than one-thousandth the width of a human hair thick can be pulled in less than a minute, by hand in the lab, Dr. Baughman said. The process easily could be industrialized, he said.
"There is no limit on how wide they can be," Dr. Baughman said.
The ability to convert carbon nanotubes into such a useful form will be a boon to many small companies trying to use them to create newer or better devices, Dr. Thomas said.
"Nanotechnology needs this," he said. "It's been hyped, and there's been a lot of expectations."
Dr. Baughman, who said the university and a collaborating Australian national lab have
Specific strength (Score:3, Informative)
Specific strength is the term they are looking for, second it is normalized to mass, not weight.
Suggest to me someone with little science/engineering background "wrote" the article, and just listed off the interesting stuff they 'heard about nanotubes'
Re:It'll never be built (Score:2, Informative)
Sheet tensile strength (Score:5, Informative)
They also built an OLED of 500 cd/m^2 with a onset voltage of 2.4V.
Re:Spider webs (Score:3, Informative)
Re:Over-simplifying? (Score:3, Informative)
Nope. I saw this presented last month at an Air Force program review, and it is exactly what they say. For example, they showed pictures of 1 m long ribbons, where the length was limited by the length of the postdoc's arm who manually pulled the sheets from the nanotube "forest".
Re:Space elevators will never work (Score:1, Informative)
Re:more efficient then a car engine? (Score:3, Informative)
Yes
Gas turbines.
Rockets.
Ram Jets.
Pulse jets.
Re:But will it slice bread? (Score:5, Informative)
I am a chemist, I work in the "nanotechnology" field, and I have spent time in Engineering/MS labs making OLEDs, PV cells, and other thin film devices. Many of "us" consider nanotubes to be the only viable "nanotechnology" at the moment because of the fact that they can be used by spraying thin layers, making entangled sheets, or other easy-to-commercialize methods of preparation. As for the hybperbole, I think the fact that you're reading an article on MSNBC should give you a clue : ) If you read the Science article they make essentially none of the claims present in the MSNBC article. In fact all they really claim is a new method for preparing NT sheets that is way better than the current methods used for preparing NT 'paper' (it really looks and feels like paper).
Yes, nanotubes are cool. Yes, they conduct electricity. Yes, they emit white light in an OLED configuration. I'm not 100% sure where they're getting the artificial muscle thing, but from what I've read (from peer reviewed journals) don't hold your breath - but I'm no expert there. What generally happens here is the inventors like to hype their discovery up (in this case a method for preparing better NT sheets) as much as possible, but in "science speak". That is, this "may be used for ___" or "has the potential for ___" and then they rattle off stuff NTs can be used for which gets all mixed up in the in article. In this case NT sheets are nothing new and most of what they're claiming has been done before (IBM even got light out of a single NT, far more impressive if you ask me), but they're doing it better with higher quality NT sheets. When it was discovered that poly(aniline) had great mechanical properties as well as interesting "chemical switching" and conductive properties there were people that were sure it was going to be used in planes, clothes, computers... You name it. Too bad it is deliquescent - D'Oh. I can't remember whether this happened before or after the discovery that poly(acetylene) had a high tensile strength and people were claiming space elevators, lightweight electric motors, etc etc. Too bad it catches fire in air in its conductive form - D'Oh D'Oh.
At the end of the day this is another step towards some real nanotechnology applications, but you're reading about it because the editors at Science decided it was worth publishing. Only in the Science article they include all the references to the past work that made it possible :) Oh, and the microwave thing is neat because the NTs will spark like crazy in your microwave oven. So will graphite, which you can try at home if you like... If you don't know NTs are essentially "rolled up" graphite sheets, so they share a lot of common properties.
Here is the abstract:
So what they did was create sheets
Re:Space elevators (Score:2, Informative)
Spelling Nazi...(obligatory) (Score:1, Informative)
Wouldn't it be Producible ?
Re:Space elevators will never work (Score:3, Informative)
First one is wrong regarding total payload mass. I'd do math to refute the statement, but it has already been done. http://trs.nis.nasa.gov/archive/00000535/ [nasa.gov]
And yeah, the travel time will likely be few days. So what? You can get to LEO in a matter of hours once everything has been built out and systems put in place to deal with any whiplash effects that jumping off before the steady-state altitude.
And it isn't 50K miles to Geo -- it is about 24K miles. I point this out simply because it seems like you are kind of 'creating data' to put it politely. http://liftoff.msfc.nasa.gov/academy/rocket_sci/s
Finally, advantage of capturing energy: again, completely off base with respect to the current design considerations. It would be a LOT cheaper ( I estimate at least by a factor of ten, but that is just a guess) to take high energy fuel up to the anchor mass (at the end of the tethor), than to design the system to actually allow both up and down capabilities.
And even if you HAVE a down capability, that by no means implies that you can capture the potential energy of a decending object. Recall that it is a 'rope', not a bar. And the rope is already in tension. I can see no solution which would allow you to gather any worthwhile amount of energy. You can't run a current through the elevator, as you would then have a stupendeous amount of magnetic drag thanks to Earths magnetic field. So no electromagnetic regen. Which doesn't matter, as *any* form of draggy braking against the cable just looks like more mass to be lifted from the perspective of the anchor mass.
If it were a solid bar than the shift of mass would do the job on its own, thanks to the whole inertia game. If we used a 'dangling rope' and litterally tied the 'Low end' to a mass, lifted it into space and then dropped it back down, you could also get the energy back, minus drag.
In summary, your entire post strikes me as pure opinion, with no basis in fact. If I am mistaken, I urge you to issue some form of defense. While I commend you for caring, I believe that you do a disservice by attacking something you don't understand, while pretending, or worse assuming, that you do.
100 GPa in perspective (Score:3, Informative)
- Molded Nylon - 75 MPa
- Plain carbon steel - 450 MPa
- 4130 Cromoly steel - 1110 MPa
- Dupont Kevlar 49 - 3620 MPa
- Carbon Fiber - 4000 MPa (approx)
As you can see, carbon fiber is about 4% as strong as the target, which tells you two things: First, nanotubes kick butt. Second, this elevator is not right around the corner. Sure they're getting good at making individual fibers, but the weave will not carry the same stress as the individual fibers, and we have to find a way to work around that.Re:Not science fiction according to IEEE Spectrum (Score:1, Informative)