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The third-normal stress difference in entangled melts: Quantitative stress-optical measurements in oscillatory shear

Kannan, R. M. and Kornfield, J. A. (1992) The third-normal stress difference in entangled melts: Quantitative stress-optical measurements in oscillatory shear. Rheologica Acta, 31 (6). pp. 535-544. ISSN 0035-4511. https://resolver.caltech.edu/CaltechAUTHORS:20200518-073137020

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Abstract

Stress-optical measurements are used to quantitatively determine the third-normal stress difference (N₃ = N₁ + N₂) in three entangled polymer melts during small amplitude (<15%) oscillatory shear over a wide dynamic range. The results are presented in terms of the three material functions that describe N₃ in oscillatory shear: the real and imaginary parts of its complex amplitude ψ*₃ = ψ′₃- iψ″₃, and its displacement ψ^d₃. The results confirm that these functions are related to the dynamic modulus by ω²ψ*² (ω)=(1-β)[G *(ω))−1/2 G *(2ω)] and ω²ψd² (ω)=(1- β)G′(ω) as predicted by many constitutive equations, where β = −N₂/N₁. The value of (1-β) is found to be 0.69±0.07 for poly(ethylene-propylene) and 0.76±0.07 for polyisoprene. This corresponds to −N₂/N₁ = 0.31 and 0.24±0.07, close to the prediction of the reptation model when the independent alignment approximation is used, i.e., −N₂/N₁ = 2/7 − 0.28.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1007/bf00367008DOIArticle
ORCID:
AuthorORCID
Kornfield, J. A.0000-0001-6746-8634
Additional Information:© 1992 Springer Verlag. Received 25 July 1992; Revised 02 September 1992.
Subject Keywords:third normal stress difference; oscillatory shear; flow birefringence; entangled melts; polyisoprene; poly(ethylene-propylene)
Issue or Number:6
Record Number:CaltechAUTHORS:20200518-073137020
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200518-073137020
Official Citation:Kannan, R.M., Kornfield, J.A. The third-normal stress difference in entangled melts: Quantitative stress-optical measurements in oscillatory shear. Rheola Acta 31, 535–544 (1992). https://doi.org/10.1007/BF00367008
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103257
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:18 May 2020 16:05
Last Modified:18 May 2020 16:05

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