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Stress optical measurement of the third normal stress difference in polymer melts under oscillatory shear

Kornfield, J. A. and Fuller, G. G. and Pearson, D. S. (1990) Stress optical measurement of the third normal stress difference in polymer melts under oscillatory shear. Rheologica Acta, 29 (2). pp. 105-116. ISSN 0035-4511. https://resolver.caltech.edu/CaltechAUTHORS:20200518-072632377

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Abstract

Results are reported for the dynamic moduli, G′ and G″, measured mechanically, and the dynamic third normal stress difference, measured optically, of a series bidisperse linear polymer melts under oscillatory shear. Nearly monodisperse hydrogenated polyisoprenes of molecular weights 53000 and 370000 were used to prepare blends with a volume fraction of long polymer, Φ_L, of 0.10, 0.20, 0.30, 0.50, and 0.75. The results demonstrate the applicability of birefringence measurements to solve the longstanding problem of measuring the third normal stress difference in oscillatory flow. The relationship between the third normal stress difference and the shear stress observed for these entangled polymer melts is in agreement with a widely predicted constitutive relationship: the relationship between the first normal stress difference and the shear stress is that of a simple fluid, and the second normal stress difference is proportional to the first. These results demonstrate the potential use of 1,3-birefringence to measure the third normal stress difference in oscillatory flow. Further, the general constitutive equation supported by the present results may be used to determine the dynamic moduli from the measured third normal stress difference in small amplitude oscillatory shear. Directions for future research, including the use of birefringence measurements to determine N₂/N₁ in oscillatory shear, are described.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1007/bf01332377DOIArticle
ORCID:
AuthorORCID
Kornfield, J. A.0000-0001-6746-8634
Fuller, G. G.0000-0002-2924-053X
Additional Information:© 1991 Springer Verlag. Received 21 June 1989; Revised 22 February 1990.
Subject Keywords:Polyisoprenes; third normal stress difference; oscillatory flow; shear stress; dynamic moduli
Issue or Number:2
Record Number:CaltechAUTHORS:20200518-072632377
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200518-072632377
Official Citation:Kornfield, J.A., Fuller, G.G. & Pearson, D.S. Stress optical measurement of the third normal stress difference in polymer melts under oscillatory shear. Rheol Acta 29, 105–116 (1990). https://doi.org/10.1007/BF01332377
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103256
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:18 May 2020 15:59
Last Modified:18 May 2020 15:59

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