Stories tagged abalone

Oct
07
2007

Ultra plastic: Just think - a Lunchable that you could see, but never get to.  (Image courtesy of the University of Michigan)
Ultra plastic: Just think - a Lunchable that you could see, but never get to. (Image courtesy of the University of Michigan)
Using a technique similar to the natural processes involved in the formation of seashells, scientists at the University of Michigan at Ann Arbor have created a plastic based material as thin as a sheet of paper, but as strong as steel.

What’s the secret? It has to do with that magic word that we love so much around the science museum: nano.

Nano-sized sheets of plastic are stacked by a robotic arm, and stuck together with a mortar made of “clay and a non-toxic glue similar to that used in school classrooms.” The plastic layers are so thin that even after 300 of them are stacked, the resulting sheet is still paper-thin and transparent. The reason why the material is so strong is because the layers are stacked in alternating patterns, and because the glue/mortar immediately creates new bonds as soon as others are broken. Again, this is all very similar to the way that abalone shells (known for their strength) form – in the case of the shells, crystals are stacked in alternating patterns, and cemented together with an organic mortar.

Currently the material is only being produced in pieces a few centimeters large, but the Ann Arbor researchers are already building a machine in their lab that could make pieces as large as one meter by one meter.

Although it’s still several years away from commercial applications, the material has potential uses ranging from microtechnology to creating stronger, lighter body armor.

Jul
08
2007

Things That Nature Does Not Fully Understand

  1. Dippin’ Dots
  2. Anime
  3. Nuclear Power Plants
  4. Internet Dating
  5. Stephen Baldwin

Things That Science Does Not Fully Understand

  1. Fireflies
  2. Photons
  3. Stephen Baldwin
  4. The Slinky
  5. Abalone Shells

Science is working on this last item, though (while Nature doesn’t even know where to begin with “Dippin’ Dots”).

Abalone shells, it just so happens, are very, very strong. They are made up of aragonite (which itself is composed of calcium carbonate, the stuff in all seashells), but the shells are 3000 times more fracture-resistant that aragonite alone. This article gives points out that you could run over an abalone shell with a truck, and it wouldn’t break; “you will crumble the outside [of the shell] but not the [nacre] inside.” Exactly how this “nacre” forms is something that has been puzzling scientists.
The Mighty Abalone: Will we ever learn your secrets?    (photo by rachaelwrite)
The Mighty Abalone: Will we ever learn your secrets? (photo by rachaelwrite)

It had been thought that the microscopic structure of nacre was something like a wall bricks or tiles stacked regularly on top of each other – aragonite bricks, with organic mortar between them. However, after having examined nacre using synchrotron radiation, or “light emitted by electrons speeding around a curved track,” scientists think that the bricks and mortar analogy might not be quite accurate.

It seems now that the “wall” is largely composed of “distinct clumps of bricks, each an irregular column of crystals with identical composition but a crystal orientation different than neighboring columns.” Scientists think the reason for this irregular structure has to do with eliminating natural planes of cleavage. “A poly-crystal,” the researchers say, “is mechanically stronger than a single crystal, so perhaps that is an advantage for the animal."

What’s more, the process for constructing the nacre is extremely efficient. The aragonite crystals, composing 95% of the structure, are self-assembled, so the organism has to manufacture only the organic mortar between them.

If we could find a synthetic way of copying biominerals like this, they could be applied in all sorts of places. “We could, for example, produce cars that absorb all the energy at the impact point but do not fracture,” says one University of Wisconsin-Madison scientist. Neat.