Effect of deformation on the wetting behavior of a viscoelastic fluid and its implication in the polymer extrusion /
In this thesis, we will present the results from our
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| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1997.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=736824081&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | In this thesis, we will present the results from our theoretical and experimental studies on the effect of deformation on the wetting behavior of a viscoelastic fluid and discuss its implications in polymer extrusion. We begin with a theoretical analysis of the effect of deformation on the common line (three-phase line of contact) motion. We use the jump entropy inequality to put a constraint on the behavior of a viscoelastic surface fluid. Combining this surface material behavior with the entropy inequality at the common line, we show that the common line motion is a function of the deformation history. To verify the conclusions of our theory, we subject molten linear low- density polyethylene (LLDPE) to shear deformation in a sliding plate rhemoeter. We find that LLDPE begins to dewet the rheometer plates above a critical shear rate, confirming our theoretical prediction that the wetting behavior of a viscoelastic fluid may change under deformation. Our experiments also show that the common line motion under oscillatory shear in a sliding plate rheometer can lead to shear stress drop, a phenomenon commonly attributed to slip at the polymer-solid interface. We conclude our study with an experimental investigation of the origin of sharkskin instability in the extrusion of LLDPE. Using the results from our studies on the common line motion, we propose a possible mechanism for the onset of this instability in the LLDPE extrusion and discuss possible connection between the common line motion and die drool. |
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| Item Description: | Vita. "Major Subject: Chemical Engineering". |
| Physical Description: | ix, 93 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 88-91. |