[geeks] Carbon nanotube buckytape

[Brian Dunbar]

Phil Stracchino wrote:
> Brian Dunbar wrote:
> 
>>Phil Stracchino wrote:
>>
>>>I don't think they've stated how strong it actually is, except "stronger
>>>than steel weight-for-weight".  Certainly the strength-to-weight ratio
>>>of individual nanotubes is more than adequate for the purpose.
>>
>>I read a summary from a fellow earlier today (but ARGH can't find it 
>>now) with the numbers.  If I can find it I'll summarize or post a link.
> 
> 
> That'd be greatly appreciated.  Facts are always better than guesswork.
> 

In the second post ( 08-19-2005, 04:27 PM ) in the thread

http://liftport.com/forums/showthread.php?t=246

"From the article:

Especially considering the absence of polymer binder, the mechanical 
properties of the aerogel-like and densified MWNT sheets are 
unexpectedly high, which is probably a consequence of the interconnected 
fibril network (fig. S2). The density-normalized mechanical strength is 
much more accurately determined than mechanical strength, because the 
sheet thickness is less reliably measured than the ratio of maximum 
force to mass-per-length in the stretch direction. Stacks of undensified 
sheets have an observed tensile strength of between 120 and 144 
MPa/(g/cm3) (fig. S5, A and B). A densified stack containing 18 
identically oriented sheets had a strength of 465 MPa/(g/cm3), which 
decreased to 175 MPa/(g/cm3) when neighboring sheets in the stack were 
orthogonally oriented to make a densified biaxial structure. These 
density-normalized strengths are already comparable to or greater than 
the http://www.sciencemag.org/math/sim.gif160 MPa/(g/cm3) strength of 
the Mylar and Kapton films used for ultralight air vehicles and proposed 
for use in solar sails for space applications (21) and those for 
ultrahigh-strength steel [http://www.sciencemag.org/math/sim.gif125 
MPa/(g/cm3)] and aluminum alloy 
[http://www.sciencemag.org/math/sim.gif250 MPa/(g/cm3)] sheets.

Sheets generally have much lower limiting strengths than do fibers of 
the same material. However, at a value of 465 MPa/(g/cm3), the tensile 
strength of the densified MWNT sheet is comparable to or exceeds 
reported values for nanotube fibers and yarns that do not include a 
binding agent: 575 MPa/(g/cm3) for forest-spun twisted MWNT yarns (12), 
500 MPa/(g/cm3) for aerogel-spun yarns (7), 105 MPa/(g/cm3) for SWNT 
yarns spun from superacids (22), and 65 MPa/(g/cm3) for SWNT yarns spun 
using an acidic coagulation bath (23). Order-of-magnitude or greater 
increases in mechanical strength have been observed when internanotube 
coupling is enhanced by polymer incorporation into nanotube sheets and 
yarns (2326), and similar strength increases might be achievable by 
infiltration of suitable polymers into the present MWNT sheets."



-- 
Brian Dunbar
System Administrator
Liftport

brian.dunbar at liftport.com
aim: bdunbar1967

Remember.
But move forward, too. Light a candle, yes. But also drive a rivet.
~Lileks