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New Carbon-based Paper Stronger Than Nanotubes
LynnwoodRooster writes "Science Magazine reports that a group from Northwestern University in Illinois has a new process for creating carbon-based paper that's stronger than nanotubes, and incredibly easy to use to make sheets of any desired sizes. Huge implications for aircraft, automobiles, and the ever-sought-after space elevator?"
Not if it's used in a composite. Ordinary carbon fibre isn't too good in water either - but that would be why it's embedded in an epoxy (or other) matrix...
Sadly, no. TFA links to the actual paper. Tensile strength is on the order of 35 GPa. We'd need 65 GPa or more from a material with density similar to graphite.
Next on the drawing board: invent a waterproof coating that is as strong as carbon-based paper... Why does the coating need to be stiff?
It doesn't have to be as strong, merely flexible...
That way it won't shatter.
Kinda like the paint we put on cars today.
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TFA states that water is the "kryptonite" of the superstrong paper. Doesn't that kill its practicality in things like planes and automobiles?
Carbon fiber is a floppy woven cloth that can be cut with scissors, but that doesn't stop people from building planes, cayaks, and golf club shafts with the stuff by making a composite with epoxy.
Carbon fiber is great stuff- its main failing is that nobody can make the stuff fast enough (or manufacturers are intentionally not ramping up capacity to milk the aerospace/defense industry.) Boeing and the USAF are buying the stuff by the football field for their planes.
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Well-yeah-sorta. In terms of organic vs. inorganic chemistry, paper has carbon so it qualifies as organic. But paper's mostly cellulose, (C6H10O5)n, so it isn't mostly carbon by weight, and certainly not all carbon like this new material.
(While I'm thinking of it, why do organic vegetables cost more? They're all organic...)
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What's you call carbon fiber is in fact composite material made of resin and carbon fiber. When the resin isn't hardened this material is flexible like leather. Many flexible tool are made of composite with carbon fiber, like arc, suspension, etc ...
Carbon fiber aren't use alone, their are a lot of different type of composite material that use carbon fiber with really different property.
That headline should read "... stronger than nanotube paper", not nanotubes. Why that's a good benchmark for strength, I have no idea. It's generally used as a filter. It's like saying cotton plants are stronger than trees because cotton paper is stronger than normal paper.
I'm 27 and we used Mimeographs (Ditto Machines). There were really good because the teachers could make cheap handouts with them, much cheaper than using a photocopier. Granted they didn't look quite as nice as a photocopier, but they sure smelled a lot better.
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Didn't early airplanes use either paper or silk for the skin, rather than metal? All they had to do to make characteristics of the medium more desirable (weatherproof, taught) was to "dope" the medium, which involved painting on a coating. Many model RC aircraft still use that technology today.
It's no different than any other composite. Silk is still an extremely attractive (oops, no pun intended) medium for composites, but very expensive compared to carbon fiber, kevlar, and fiberglass cloths. But, with any of those modern materials used in composites, the tensile strength is one thing, but torsional stiffness is nonexistent, and the materials are not waterproof. Resin by itself has extremely good torsional strength, but very little tensile strength and is very brittle. So, the solution is to make a sandwich of materials with each desirable characteristic, resulting in a composite material which will have the most desirable characteristics of each composite component, but without the undesirable characteristics. Carbon fibre is protected from UV, water, and abrasion by the epoxy (and usually a additional layer of protection using acrylic, lacquer, or other coating - in other words paint), and the resin provides torsional stiffnes by itself AND by bonding several layers of the cloth together, which utilizes the tensile strength of each composite to further increase torsional strength without becoming brittle.
Why should paper be any different? The bonding techniques will be different, sure, but this discovery is the first step. The next step is to either devise a new bonding process which is as reliable as "conventional" composites, or to find a way to use this process to develop new fibers which can be used in conventional composite construction techniques.
It would be interesting to see how this development affects experimental aircraft. Can a Long-EZ or Cozy MkIV be made lighter with this new material, without sacrificing airframe strength and without lengthening build time?
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For those interested, here's the news@nature article, as well as the original research paper. Here's a paste of the abstract:
Preparation and characterization of graphene oxide paper
Dmitriy A. Dikin1, Sasha Stankovich1, Eric J. Zimney1, Richard D. Piner1, Geoffrey H. B. Dommett1, Guennadi Evmenenko2, SonBinh T. Nguyen3 & Rodney S. Ruoff1
Free-standing paper-like or foil-like materials are an integral part of our technological society. Their uses include protective layers, chemical filters, components of electrical batteries or supercapacitors, adhesive layers, electronic or optoelectronic components, and molecular storage1. Inorganic 'paper-like' materials based on nanoscale components such as exfoliated vermiculite or mica platelets have been intensively studied2, 3 and commercialized as protective coatings, high-temperature binders, dielectric barriers and gas-impermeable membranes4,5. Carbon-based flexible graphite foils5, 6, 7 composed of stacked platelets of expanded graphite have long been used8, 9 in packing and gasketing applications because of their chemical resistivity against most media, superior sealability over a wide temperature range, and impermeability to fluids. The discovery of carbon nanotubes brought about bucky paper10, which displays excellent mechanical and electrical properties that make it potentially suitable for fuel cell and structural composite applications11, 12, 13, 14. Here we report the preparation and characterization of graphene oxide paper, a free-standing carbon-based membrane material made by flow-directed assembly of individual graphene oxide sheets. This new material outperforms many other paper-like materials in stiffness and strength. Its combination of macroscopic flexibility and stiffness is a result of a unique interlocking-tile arrangement of the nanoscale graphene oxide sheets.
Not in the slightest. It just won't be a drop-in replacement for aluminum.
All materials have their strengths and weaknesses. Think of something more like a house... Wood doesn't do too well with water, so the roof is coated with weak, non-structural materials like asphalt shingles or tile. In fact most structural building materials don't do too well with exposure to water and are shielded in some way.
It's not hard to imagine this carbon paper being used to construct structural beams of airplanes and automobiles, being coated with rubber or tar for last-line protection, and having the skin made of other materials that aren't at all susceptible to water (aluminum, fiberglass, or composites).
Of course, we don't know that is going to be an issue to begin with. They seem to be looking into materials other than water to bond the carbon, so this could all be a moot point.
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35 GPa refers to elastic modulus, not tensile strength.
Carbon fiber for example has an elastic modulus of 60-600 GPa and tensile strength of about 6GPa
Maybe this somehow got mixed up?
don't cut it off www.mgmbill.org
It also rots. My neighbour had a Pacer whose fabric rotted out and he had to get the wing recovered.
Silk is often referred to as "stronger than steel". That may be true per unit density (strength/weight), it really doesn't matter because silk is useless as a structural due to it's low stiffness. Young's modulus is around 100 or 200 MPA, whereas aluminum is about 70,000 and steel is 200,000.
There is no such thing as the torsional strength of a material. Structures have torsional strength, not materials. Materials have shear strength, and the shear strength of even the very very best polymers are negligible compared to common structural materials. The shear strength of common high-performance epoxies used in aircraft composites are maybe 5 ksi when you account for moisture absorption and service temperature, whereas 2024 aluminum is maybe 30 ksi.
Resin doesn't have good "torsional" (shear) strength, it has bad shear strength. Ditto for the tensile strength. Again, compared to most structural materials, most polymers (resins) have high elongation to failure but that varies widely depending on the amount of crosslinking of the hydrocarbon chains. Within the epoxies, you can formulate ones that have low crosslinking and stretch like bubblegum, or you can crosslink the bejeepers out of them and create glass. It depends on the chemistry.
Actually, the resin together with the fibers forms a microstructure that becomes a material continuum from the macro perspective. That is, the composite is actually a structure on a microscopic scale, but from an engineering point of view it is viewed as a material with properties derived using classical lamination theory. So the purpose of the matrix (resin) is structural, you could say to support the fibers that carry the actual load. The paint is required to protect the matrix from UV and moisture as most polymers are susceptible to both.
The resin doesn't provide any of the stiffness, the fibers do all that, the resin (matrix) supports the fibers so they can do their job. The shear stiffness and strength of the laminate stack come from plies at 45 degrees to the load application direction. Mohr's circle for pure shear tells us that you get pure tension and compression in the 45 degree directions, which the fibers can carry. It's quite clever and is the classic example of structural tailoring.
A million reasons. How resistant the material is to delamination would be my first question. Hidden delamination and it's effect on compression strength was carbon/epoxy's Achilles heel for a long time. Getting the matrix (epoxy?)
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