---------- Forwarded message ----------
Date: Thu, 16 Nov 2000 13:18:10 PST
From: AFP <C-afp@clari.net>
Newsgroups: clari.world.europe.france, clari.tw.science, clari.world.europe,
clari.tw.misc, clari.tw.science+space
Subject: Spun nanotubes spell breakthrough
PARIS, Nov 16 (AFP) - French researchers reported Thursday they
had achieved a breakthrough in making carbon nanotubes, one of the
most exciting inventions of the past decade, which could open the
way to manufacturing them as fibres with a host of uses.
Nanotubes, first invented in 1991, are tubes with a diameter far
smaller than a human hair, with a carbon structure that makes them
chemically inert but light, extremely strong and resilient, as well
as able to conduct heat and electricity.
They are conventionally created by vaporising graphite rods by
electric arc in a chamber filled with a gas such as helium or
hydrogen, and then allowed to cool slowly.
Scientists from the Paul Pascal Research Centre at the
University of Bordeaux said they had devised a method to spin
single-wall nanotubes into "indefinitely long" ribbons and fibres.
Unlike other carbon fibres, they are extremely flexible and can
even be knotted without breaking, they reported. Their research is
published in full in Friday's issue of Science, the US weekly
journal.
Ultra-strong fibres of this kind have a wide variety of
potential applications, from artificial muscles to hydrogen storage
and flat-screen TVs, the researchers hope.
The ribbons were created by dispersing raw nanotube soot into a
surfactant, or detergent, solution.
That solution was then injected into a flowing steam of polymer
solution which caused the nanotube material to recondense into a
mesh. The flow of the solution aligned the mesh into ribbon-like
fibres.
On November 2, separate teams from Japan's NEC Corp. and the
Hong Kong University of Science and Technology reported they had
created the smallest nanotubes feasible, each narrower than a
filament of DNA.
The tubes were just 0.4 nanometres (0.4 billionths of a metre)
wide.
Scientists have previous created even smaller tubes, of 0.33
nanometres. However, these are unstable because structural changes
at this tiny scale can force carbon to become metallic.
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