Hi All,
There seems to be some interest in aligning carbon nanotubes in one direction.
What if one mixed aggregate carbon nanotubes with molten PE or PE and then extruded. Then using the method after Damascus Steel, keep melting, stretching and folding over 10's , 100's , 1000's of times. The carbon nanotubes would be eventually aligned in one direction.
Now to remove the PE or PP matrix?? Possibly it could be vaporized off.
Richard Saam
Along with the nanotubes.
Fine idea, but I think it was recently published that PVA was used. Co-extrusion I believe. Although the Japanese folding method or Damascus process was not applied and seems viable. I'd call in a taffy puller if enough material could be amassed.
Dr. K
Hallo, sounds to me that what is needed is the resin or binder that is used in injection moulding of metals.
I don't know the process in detail, but I believe that the metal powder is injection moulded on "normal" machines, e.g. Arburg, into a green state, using a binder which is similar to wax or low M.Wt. PE.
The soft parts are then placed in an oven and the binder is "evaporated", leaving the parts in a "brown" state. The metal powder is then fused to form the finished part by a process like sintering.
W There seems to be some interest in aligning carbon nanotubes in one direction. What if one mixed aggregate carbon nanotubes with molten PE or PE and then extruded. Then using the method after Damascus Steel, keep melting, stretching and folding over 10's , 100's , 1000's of times. The carbon nanotubes would be eventually aligned in one direction.
Now to remove the PE or PP matrix?? Possibly it could be vaporized off.
You can't get that high of draw ratios with PE or PP ... unless you work with gelled UHMWPE and spin it. Pricey.
John
I know Dr. Frank Ko's group at Drexel has worked with CNTs and electrospinning. The result is a sub-micron sized polymer fibers encapusulating CNTs. The polymer could be vaporized off or dissolved away using the proper solvents.
The problem with electrospinning is that you can't control fiber orientation very successfully. Non-woven felt-like mats are usually produced in the process.
JCS
Using glass fibers as analogy for nanotubes, during processing under high shear conditions, the glass fibers line up in the flow directions. One would expect the nanotubes to do the same (provided they have a high enough aspect ratio [length/width]). Extrude or injection mold a resin containing the nanotubes, and the Damascus Steel process may not be needed. To maximize shear, use highly viscous (high MW) polymer, and force the blend through very small and long die.
As you suggest, you can decompose or burn off the polymer, but be aware of fire and explosion potential of gases generated.
Regards,
Ernie
Hello,
We have results of nanotubes /PP composites fibers which have been stretched in order to align nanotubes along the axis of the fiber using common polymer equipment. Tenacity of the fibers is superior to Kevlar and similar to UHMWPE Dyneema with only 3%wt. of MWNT.
Injection molding do not align nanotubes which are wavy, so you do not get any significative reinforcement.
Fiber Composites manufacturing needs a binder to provide adhesion. Its mechanical contribution is small compared to the contribution of the high modulus or strength fibers.
BTW, half of the fuel lines in cars in the US contains already MW nanotubes.
Olivier Nanocyl
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