Comments on: Carbon nanotubes could be a Kevlar killer

By: Mu

Mu — Tue, 22 Sep 2009 13:42:08 +0000

To give you an idea on today’s pricing, I just ordered a kg of “low grade” MWNT for $3.5k. This is still a factor of 10 above the guy’s target price. Unless he’s not really using nanotubes but nanofibers, those can be had for 1k/kg. But those are hard to get untangled at reasonable length.

By: Steve

Steve — Tue, 22 Sep 2009 10:13:42 +0000

very interesting guys.

By: Clodboy

Clodboy — Tue, 22 Sep 2009 10:09:47 +0000

jdun: AFAIK, the US Armed Forces and various law enforcement agencies have been trying to phase out Kevlar in favor of Zylon, although that too seems to be falling out of favor now that it has been discovered to degrade fairly quickly over time.

So yes, High Modulus Polyethylene (“Dyneema”) is probably the way to go for the time being.

By: Michael

Michael — Tue, 22 Sep 2009 05:00:48 +0000

CNTs have tremendous possibility for armor applications, pretty much anywhere that kevlar is now utilized. But, as R.A.W has pointed out, volume production of CNTs remains a problem, but it has been advancing quite rapidly. The cost of such an item is primarily dependent on the tolerances, wether it requires CNTs of consistent thickness and of what individual length. I have been out of the nano-research field for a couple years now, but I find it interesting that in the article Antoinette says that in 4 years he’ll be producing it at $10 for 35 grams (or $.30/gram). Wikipedia says that in 2007 the price for SWCNTs was $100/gram. So, he has a significant way to go still, if he hopes to make that price. I would assume that his price is a simple extrapolation of the improvements in process over the past 5 years– i.e. assuming that we can repeat that progress. Four years is a long time in business, but not always in science. That timeline is long enough that I seriously doubt that he honestly knows how to make them that cheap. But the performance claims are real.

By: R.A.W.

R.A.W. — Tue, 22 Sep 2009 04:32:15 +0000

Carbon nanotubes (fullerenes) do indeed have extremely high theoretical strength, but making them long enough has heretofore been a problem, as has getting them to stay in any sort of composite matrix (they're rather slippery). They're also pricey to produce in any significant bulk, and they've shown some worrying incompatibility with living cells. On the other hand, they have some very interesting electrical properties and are of course very small. I suspect that they will become common in electronics before they become common in structural components. But we shall see; perhaps nanocomp is on to something.

By: jdun1911

jdun1911 — Mon, 21 Sep 2009 23:00:46 +0000

Aren’t they replacing Kevlar with polyethylene fiber? Kevlar isn’t the best soft body armor to use in hot or rainy weather.

By: Mr.Tolliver

Mr.Tolliver — Mon, 21 Sep 2009 15:54:22 +0000

I wouldn’t say carbon nanotubes (CN’s) would kill Kevlar. I’m guessing here, since I have yet to see a patent about this, that those sheets are made up of fibers heavily reinforced with milli/micrometer CN fibers. We have yet to see continuous CNs making up bulk matter. Still even just by throwing in CNs in the processing of normal fibers would still increase their tensile strength, toughness, and etc. Its nice to see at least a greater introduction of CNs in the marketplace.

By: Mu

Mu — Mon, 21 Sep 2009 14:52:40 +0000

While carbon nanotubes itself are very strong, materials made from them have been rather disappointing. The values reported of this material are still half what you can get for high strength conventional carbon fiber, Toray T1000 reports 6.4 GPa. The one thing they might have going for them is better impact tolerance, since it’s a yarn it might have more “give” than the rather brittle carbon fibers.
As for the rifle round stopping material, that will have a LONG way to go. You still need the impact plate to dull the tip or it will cut through any fabric like butter. The fiber is only good if you get to load it in tension by spreading the load.

By: Vitor

Vitor — Mon, 21 Sep 2009 12:27:10 +0000

If carbon nanotubes deliver their potential, it will cause a turmoil in the armies around the world, since any caliber that is not a .30 with a tugsten sabot would be very innefective against such body armor.

By: Clodboy

Clodboy — Mon, 21 Sep 2009 11:26:41 +0000

Diamonds, though just a crystal lattice of carbon atoms, are the hardest known naturally occuring substance; carbon nanotubes promise to combine this kind of hardness with the tensile strength and conductivity of steel, and the high flexibility and low weight of plastics.

The neat thing is that just like with diamonds, carbon atoms will readily assemble into these tubular structures given the right conditions – the problem is that to utilize their full potential, the tubes have to be of parallel orientation and sufficient length (i.e. milimeter-sized, which may not seem like much until you consider their diameter is around 1 nanometer, i.e. a millionth of its length), which requires considerable finetuning of the method.

But given the advances made in nanotube production in the last few years, there is little doubt that they will find widespread acceptance in the decades to come.