Coupling between flow and diffusion at polymer/polymer interfaces: large amplitude oscillatory shear experiments |
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Authors: | Hua Qiu Mosto Bousmina John M Dealy |
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Institution: | (1) Department of Chemical Engineering CERSIM, Laval University, Sainte-Foy Québec (QC), G1K 7P4. Canada e-mail: Bousmina@gch.ulaval.ca, CA;(2) Department of Chemical Engineering McGill University, 3610 University Street Montréal (QC), H3A 2B2, Canada, CA |
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Abstract: | Coupling between flow and diffusion at symmetric polymer/polymer interfaces has been investigated. Polystyrene/polystyrene
sandwich assemblies were subjected to large-amplitude oscillatory shear (LAOS) using a sliding-plate rheometer (SPR) and the
stress was monitored as a function of time. The results were treated using a new model combining Wagner's model with the theory
of Doi and Edwards. The model explicitly expresses the influence of the strain and stress amplitudes frequency and time on
the self-diffusion process. The apparent self-diffusion coefficient was found to increase with welding time, in agreement
with our previous results obtained using small-amplitude oscillatory shear measurements. However, it was found in the present
case that the self-diffusion coefficient depends strongly on the strain and stress amplitudes and frequency, and its steady
state value was found to be larger than that determined from small-amplitude oscillatory shear measurements. It appears that
the large strain oscillatory shear field continuously increases the density of chain ends at the interface and thus increases
the flux of mass transport.
Received: 30 January 2001 Accepted: 12 June 2001 |
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Keywords: | Diffusion Interface LAOS Integral models |
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