2026-09-21T00:23:12Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/22112 2023-07-10 col_2142_5131 col_2142_11615 com_2142_5130 com_2142_9130 com_2142_8903

McHugh, Anthony J. Guy, R. Kirk 2011-05-07T13:29:20Z 2011-05-07T13:29:20Z 10000-01-01 1992 The effects of shearing and elongational flows on flow induced crystallization in polymer melts were investigated for the two-phase system of high molecular weight polyethylene suspended in a linear low density polyethylene carrier phase. Shearing flow was produced by a counter-rotating couette device and elongational flow was produced by means of a four roller mill device. Deformation and bursting of droplets were observed in both of these flows, however, shearing flow was found unsuitable for quantitative studies, since the orientation of the optical axes in the carrier and suspended phases were not coaxial. Hot stage and dichroism studies indicated that crystallization occurs in the suspended phase in the four roller mill, at temperatures above which quiescent crystallization would occur. In-situ birefringence measurements were made and initial crystallization rates were determined and found to depend upon both stress and strain in the deforming droplet. This was very suggestive of a viscoelastic phenomenon, not simply, a nucleation and growth controlled mechanism, thus the separability, of flow effects and nucleation and growth crystallization, is brought into question by this complex behavior. A first order approximation based on molecular rheology has been used to gain qualitative and quantitative insights on the observed trends. Made available in DSpace on 2011-05-07T13:29:20Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9236476.pdf: 4778887 bytes, checksum: 29143483440b3acd250e5605c3b47e0f (MD5) Previous issue date: 1992 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:55:24Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:25:49-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9236476 (UMI)AAI9236476 http://hdl.handle.net/2142/22112 eng Copyright 1992 Guy, R. Kirk Engineering, Chemical A study of flow-induced crystallization in two-phase polymer melts text Chemical and Biomolecular Engineering Chemical Engineering University of Illinois at Urbana-Champaign Dissertation Ph.D.