The anisotropy of simple shearing flow
article
The optical analogue of the second normal stress difference, namely, n22 -n33 has been measured for several polymer systems. The experimental method is direct and makes use of capillary and slit dies. For the polymer melts examined - ranging from a polystyrene with a viscosity of 104 Ns/m2 to a PIB of viscosity 50 Ns/m2 - a non-zero (n22 -n33) was found which could not be accounted for by any systematic errors. Except for one case, where (n11 -n22) could not be evaluated, the ratio (n22 -n33)/(n11 -n22) was found to be negative with an absolute value of 0.05 to about 0.1. For solutions the results are not clear-cut: in several cases n22 -n33 was immeasurably small but in one case (23% PIB in oil) the above ratio was the same as for the melts. A modification of the (dilute solution) molecular theories is suggested which is qualitatively able to describe most of the experimental results here outlined. © 1973 Dr. Dietrich Steinkopff Verlag.
TNO Identifier
227412
ISSN
00354511
Source
Rheologica Acta, 12(1), pp. 25-34.
Publisher
Steinkopff-Verlag
Pages
25-34
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