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Real-time depth sectioning: Isolating the effect of stress on structure development in pressure-driven flow

Fernandez-Ballester, Lucia and Thurman, Derek W. and Kornfield, Julia A. (2009) Real-time depth sectioning: Isolating the effect of stress on structure development in pressure-driven flow. Journal of Rheology, 53 (5). pp. 1229-1254. ISSN 0148-6055.

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Transient structure development at a specific distance from the channel wall in a pressure-driven flow is obtained from a set of real-time measurements that integrate contributions throughout the thickness of a rectangular channel. This “depth sectioning method” retains the advantages of pressure-driven flow while revealing flow-induced structures as a function of stress. The method is illustrated by applying it to isothermal shear-induced crystallization of an isotactic polypropylene using both synchrotron x-ray scattering and optical retardance. Real-time, depth-resolved information about the development of oriented precursors reveals features that cannot be extracted from ex-situ observation of the final morphology and that are obscured in the depth-averaged in-situ measurements. For example, at 137 °C and at the highest shear stress examined (65 kPa), oriented thread-like nuclei formed rapidly, saturated within the first 7 s of flow, developed significant crystalline overgrowth during flow and did not relax after cessation of shear. At lower stresses, threads formed later and increased at a slower rate. The depth sectioning method can be applied to the flow-induced structure development in diverse complex fluids, including block copolymers, colloidal systems, and liquid-crystalline polymers.

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Kornfield, Julia A.0000-0001-6746-8634
Additional Information:©2009 The Society of Rheology. Received 24 February 2009; revised 10 June 2009. Financial support for this work was provided by the National Science Foundation under Grant Nos. DMR-0505393 and DMI-0218112, and by the ARCS Foundation. We are grateful to Dr. Weijun Zhou and Dr. R. L. Sammler of Dow Chemical Co. for kindly providing the materials used in this study. We thank Jan Willem Housmans for microfocus measurements, and Lixia Rong and Igors Sics for help with experimental setup at X27C (NSLS). We acknowledge NSLS and ESRF for providing beamtime and facilities.
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Arcs FoundationUNSPECIFIED
Subject Keywords:channel flow, crystallisation, polymer blends, rheology, shear strength, X-ray scattering
Issue or Number:5
Classification Code:PACS 83.50.Ha Flow in channels (rheology); 47.60.Dx Flows in ducts and channels; 64.70.dg Crystallization of specific substances (solid-liquid transitions); 83.80.Uv Block copolymers (rheology); 78.70.Ck X-ray scattering (condensed matter) 83.85.Hf X-ray
Record Number:CaltechAUTHORS:20091022-125318589
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Official Citation:Real-time depth sectioning: Isolating the effect of stress on structure development in pressure-driven flow Lucia Fernandez-Ballester, Derek W. Thurman, and Julia A. Kornfield, J. Rheol. 53, 1229 (2009), DOI:10.1122/1.3164970
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16455
Deposited By: George Porter
Deposited On:22 Oct 2009 21:26
Last Modified:03 Oct 2019 01:12

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