Structural Nanotubes Now?

It has been a while—quite awhile—since I’ve made a posting. The new energy technology company of which I am a cofounder has take up nearly all my time and energies, and much of the information I would have wanted to post is now proprietary and thus I can only make mentions of areas peripheral to my own research efforts—areas which, unfortunately, I do not research intensively as a rule.

Occasionally, however, interesting companies and individuals still contact me, and one very interesting firm did so last week, namely Nanocomp Technologies located in Concord, New Hampshire.

Vendors of carbon nanostructures are, if not commonplace, sufficiently numerous now that one needs a constantly updated industry directory just to keep track of them all. None is doing big business as yet, but all have hopes of doing so, and, given the precipitate price declines of late, one might be pardoned for assuming that carbon nano is just about to go mainstream.

Price, however, is but one of the challenges facing the carbon nano crowd today. The fact is that the usefulness of the materials has yet to be established in very many applications, and without applications carbon nano is a solution looking for a problem.

Carbon nanostructures have many admirable properties but in existing forms pose many problems for those who would incorporate them in real products, and here I’ll focus on structural composites because the work I’ve done with conductive nanostructures is proprietary and not subject to open discussion.
So what’s wrong with tiny carbon as a structural material?

Lots of things, at least that has been the case to date, but first let’s restate the widely publicized virtures.

Carbon nanostructures have the highest tensile strength of any material known. They can be made to be self lubricating, highly conductive or highly resistive, and highly resistant to corrosive environments and elevated temperatures.

Unfortunately, they have many liabilities as well, at least in the forms developed to date.
Most such structures are extremely short, mere millimeters at best. That makes them difficult to form into a long filaments for use in advanced composites similar to existing glass or carbon reinforced plastics. They are also difficult to bond with adhesives and tend to clump or agglomerate when used in a resin matrix. Finally, they are difficult and costly to manufacture.

Even small additions of short fibers within an epoxy based conventional carbon fiber composite will increase the strength to weight ratio of that composite significantly, and partial carbon nano composites are starting to appear in the marketplace. But the overall promise of the technology has not been fulfilled.

Nanocomp’s president, Peter Antoinette thinks he can change that. “We can spin yarn at any given length and sell fabrics measuring several square meters. Our products are available now on special order, and we’re looking particularly at the aircraft industry.”

Antoinette further states that his yarn is actually fabricated out of rather short carbon nano filaments, and that the resulting fabrics are only microns thick and must be utilized in multi-layer layups. He further indicates that prepregs have already been made, and that common epoxy and vinylester resins are suitable for use in the same. He indicates as well that the composites have excellent ballistic properties and outperform Kevlar and Spectra for impact resistance. Since brittleness has been the signal deficiency of conventional carbon prepregs, that’s a significant advance.

If Antoinette’s claims are true, Nanocomp is in a unique position at this moment in the composite industry. No other company is selling pure carbon nano fiber structural composites, and if the predicted properties are indeed present in the materials, they would enable the construction of structures weighing a fraction of comparable structures made of Kevlar or conventional carbon fiber composites.

It is certainly much too soon to predict the ultimate impact of these innovations, and is possible that Nanocomp may be overtaken by competitors with somewhat different design approaches. Already university researchers have succeeded in growing raw filaments measuring in the meters and surely those would be more suitable for forming fabrics. Still, I would rate this as the most encouraging development I’ve seen in a decade of watching the carbon nano industry, and Nanocomp Technologies is a firm that I will continue watching.