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November 22nd, 2010

Foiled plans might or might not be good

Abstract:
Aluminum foil has long held its own as a barrier material, but there are competitors.

Nano-films

For the past several years, nanotechnology has been evaluated for its potential as a type of "smart packaging." It involves platelets so small that the unit of measure is the nanometer (one-billionth of a meter); hence, the platelets are as small as molecules, sometimes smaller. The composition of the platelets is mineral, clay, for example. But rather than being deposited on the film's surface the platelets are embedded throughout the film's thickness. The result is supposed to be an increased barrier to gases and moisture. Those molecules can't permeate through the layered platelets, necessitating that the molecules travel around and between. The winding path can amount to a distance that's multiple times greater than the thickness of the film. That being as it is, permeation is not prevented; rather, permeation is slowed. That pertains to permeation into as well as out of the packaging. Sufficient? Depends on how long the barrier is needed. Furthermore, nano-platelets typically don't render a film opaque, a decided disadvantage if barrier against light is required.

There are some high hurdles to be cleared before nanotechnology fulfills its potential regarding barrier films. One is technological: the need for greater control over the patterns in which the platelets are aligned and layered. Another is social: the need for greater knowledge about the potential effects of nano-particles on human health.

Source:
packworld.com

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