Reynolds, Carl, Thompson, Richard and McLeish, Tom orcid.org/0000-0002-2025-0299 (2018) Pressure and shear rate dependence of the viscosity and stress relaxation of polymer melts. Journal of Rheology. pp. 631-642. ISSN 1520-8516
Abstract
The pressure dependencies of polymer viscosity and stress relaxation are an important but often overlooked aspect of the material processing and postprocessing properties. We show how these dependencies can be isolated in a single measurement and can be related to the characteristic relaxation times of the material. Using a multipass rheometer (a small volume double piston rheometer), a polystyrene melt was confined at 170 °C and pressure range 1-100 bar. The pressure drop over a contraction-expansion geometry and stress birefringence were monitored as a function of shear rate, shear history, and applied pressure. Relaxation times, extracted from the stress decays correspond closely to the Rouse and reptation times of the polymer and the contributions of each mode are determined by the relationship between the shear rate and relaxation times established from linear rheology. Increasing the applied pressure caused an increase in viscosity and the measured relaxation time, but no effect on relaxation times was observed with shear rate. The technique allows the extraction of relaxation data following deformation at high shear rates and pressures, conditions more akin to industrial processing than conventional shear rheology.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 The Society of Rheology. |
Dates: |
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Institution: | The University of York |
Academic Units: | The University of York > Faculty of Sciences (York) > Physics (York) |
Depositing User: | Pure (York) |
Date Deposited: | 22 Mar 2021 12:40 |
Last Modified: | 02 Apr 2025 23:14 |
Published Version: | https://doi.org/10.1122/1.5012969 |
Status: | Published |
Refereed: | Yes |
Identification Number: | 10.1122/1.5012969 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:172392 |