This series of
images shows different degrees of "sharkskin" distortion in
the common plastic polyethylene. The faster you try to push molten polyethylene
through a die, the stronger the distortion becomes. These new images,
presented at a Society of Rheology meeting, were made by sending polyethylene
through a transparent sapphire tube and taking pictures with a high-speed
video camera. Sharkskin is an undesired effect in many polymer processes,
and the new work helps to provide insight into its causes--and solutions.
(Courtesy Flynn/Migler, National Institute of Standards and Technology)
K.B. Migler, F. Qiao, and K. Flynn (http://www.rheology.org/sor012/abstract.asp?PaperID=83)
at the 72nd Annual Meeting of The Society of Rheology, Hilton Head,
S.C., February 12-15, 2001.
Science News Service Report
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