{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/21649"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/21649","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"A study of transient flow-induced crystallization of polymer melts","abstract":"Flow-induced crystallization of several polymer systems has been studied using a four-roll mill device, coupled with optical polarimetry, to provide an in-situ technique for monitoring the transformation kinetics both during and following flow. The use of a crystallizable droplet phase, suspended within a non-crystallizable carrier phase, prevents die blockage and allows for direct measure of the droplet phase kinematics. Both birefringence and dichroism are used to investigate the crystallinity development within the deforming droplet. Birefringence studies suggest that the initial rate of crystallization is a function of both the induced stress and strain within the deformed material. Pre-crystallinity during the flow regime, prior to flow cessation, is required to achieve reproducible stress-strain behavior. Unlike birefringence studies, the dichroism studies allowed the study of the transient crystallization occurring during the flow regime. Induction times to crystallinity were found to correlate with the extension rate during the deformation. Rheological studies of the polymer systems were performed, wherein viscoelastic data and relaxation time constants were determined. A theoretical model for flow-induced crystallization was developed using a modified strain-induced crystallization model, coupled with the Hamiltonian Bracket formalism, to account for the dynamics of flow. A variety of flow kinematics and their effect on flow-induced crystallization are modeled. A non-linear force factor is incorporated to account for the finite extensibility of the molecule. The model is compared to experimental data and does predict qualitatively the effects of the flow field on crystallization.","abstract_html":"Flow-induced crystallization of several polymer systems has been studied using a four-roll mill device, coupled with optical polarimetry, to provide an in-situ technique for monitoring the transformation kinetics both during and following flow. The use of a crystallizable droplet phase, suspended within a non-crystallizable carrier phase, prevents die blockage and allows for direct measure of the droplet phase kinematics. Both birefringence and dichroism are used to investigate the crystallinity development within the deforming droplet. Birefringence studies suggest that the initial rate of crystallization is a function of both the induced stress and strain within the deformed material. Pre-crystallinity during the flow regime, prior to flow cessation, is required to achieve reproducible stress-strain behavior. Unlike birefringence studies, the dichroism studies allowed the study of the transient crystallization occurring during the flow regime. Induction times to crystallinity were found to correlate with the extension rate during the deformation. Rheological studies of the polymer systems were performed, wherein viscoelastic data and relaxation time constants were determined. A theoretical model for flow-induced crystallization was developed using a modified strain-induced crystallization model, coupled with the Hamiltonian Bracket formalism, to account for the dynamics of flow. A variety of flow kinematics and their effect on flow-induced crystallization are modeled. A non-linear force factor is incorporated to account for the finite extensibility of the molecule. The model is compared to experimental data and does predict qualitatively the effects of the flow field on crystallization.","abstract_has_math":false,"creators":["Bushman, Alexander Craig"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Chemical Engineering","degree_department":null,"school":null,"contributors":["McHugh, Anthony J."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T13:14:59Z","date_published":"2011-05-07T13:14:59Z","updated_at":"2026-07-22T22:25:18Z","subjects":["Chemistry, Polymer","Engineering, Chemical"],"languages":["eng"],"rights":["Copyright 1995 Bushman, Alexander Craig"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9624297","(UMI)AAI9624297"],"render_values":[{"text":"AAI9624297","href":null,"code":true},{"text":"(UMI)AAI9624297","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/21649","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["McHugh, Anthony J."]},{"key":"dc:creator","label":"Author","values":["Bushman, Alexander Craig"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T13:14:59Z","10000-01-01","1995"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Chemistry, Polymer","Engineering, Chemical"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1995 Bushman, Alexander Craig"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9624297","(UMI)AAI9624297","http://hdl.handle.net/2142/21649"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Flow-induced crystallization of several polymer systems has been studied using a four-roll mill device, coupled with optical polarimetry, to provide an in-situ technique for monitoring the transformation kinetics both during and following flow. The use of a crystallizable droplet phase, suspended within a non-crystallizable carrier phase, prevents die blockage and allows for direct measure of the droplet phase kinematics. Both birefringence and dichroism are used to investigate the crystallinity development within the deforming droplet. Birefringence studies suggest that the initial rate of crystallization is a function of both the induced stress and strain within the deformed material. Pre-crystallinity during the flow regime, prior to flow cessation, is required to achieve reproducible stress-strain behavior. Unlike birefringence studies, the dichroism studies allowed the study of the transient crystallization occurring during the flow regime. Induction times to crystallinity were found to correlate with the extension rate during the deformation. Rheological studies of the polymer systems were performed, wherein viscoelastic data and relaxation time constants were determined. A theoretical model for flow-induced crystallization was developed using a modified strain-induced crystallization model, coupled with the Hamiltonian Bracket formalism, to account for the dynamics of flow. A variety of flow kinematics and their effect on flow-induced crystallization are modeled. A non-linear force factor is incorporated to account for the finite extensibility of the molecule. The model is compared to experimental data and does predict qualitatively the effects of the flow field on crystallization.","Made available in DSpace on 2011-05-07T13:14:59Z (GMT). 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The use of a crystallizable droplet phase, suspended within a non-crystallizable carrier phase, prevents die blockage and allows for direct measure of the droplet phase kinematics. Both birefringence and dichroism are used to investigate the crystallinity development within the deforming droplet. Birefringence studies suggest that the initial rate of crystallization is a function of both the induced stress and strain within the deformed material. Pre-crystallinity during the flow regime, prior to flow cessation, is required to achieve reproducible stress-strain behavior. Unlike birefringence studies, the dichroism studies allowed the study of the transient crystallization occurring during the flow regime. Induction times to crystallinity were found to correlate with the extension rate during the deformation. Rheological studies of the polymer systems were performed, wherein viscoelastic data and relaxation time constants were determined. A theoretical model for flow-induced crystallization was developed using a modified strain-induced crystallization model, coupled with the Hamiltonian Bracket formalism, to account for the dynamics of flow. A variety of flow kinematics and their effect on flow-induced crystallization are modeled. A non-linear force factor is incorporated to account for the finite extensibility of the molecule. The model is compared to experimental data and does predict qualitatively the effects of the flow field on crystallization.","Made available in DSpace on 2011-05-07T13:14:59Z (GMT). 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