{"id":{"repo_id":"unt","oai_identifier":"info:ark/67531/metadc3619"},"canonical_url":"https://search.dev.ndltd.org/etd/unt/info:ark/67531/metadc3619","repository":{"repo_id":"unt","name":"University of North Texas","base_url":"https://digital.library.unt.edu/oai/"},"display":{"title":"Bulk and Interfacial Effects on Density in Polymer Nanocomposites","abstract":"The barrier properties of polymers are a significant factor in determining the shelf or device lifetime in polymer packaging. Nanocomposites developed from the dispersion of nanometer thick platelets into a host polymer matrix have shown much promise. The magnitude of the benefit on permeability has been different depending on the polymer investigated or the degree of dispersion of the platelet in the polymer. In this dissertation, the effect of density changes in the bulk and at the polymer-platelet interface on permeability of polymer nanocomposites is investigated. Nanocomposites of nylon, PET, and PEN were processed by extrusion. Montmorillonite layered silicate (MLS) in a range of concentrations from 1 to 5% was blended with all three resins. Dispersion of the MLS in the matrix was investigated by using one or a combination of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Variation in bulk density via crystallization was analyzed using differential scanning calorimetry (DSC) and polarized optical microscopy. Interfacial densification was investigated using force modulation atomic force microscopy (AFM) and ellipsometry. Mechanical properties are reported. Permeability of all films was measured in an in-house built permeability measurement system. The effect of polymer orientation and induced defects on permeability was investigated using biaxially stretched, small and large cycle fatigue samples of PET and nylon nanocomposites. The effect of annealing in nylon and nanocomposites was also investigated. The measured permeability was compared to predicted permeability by considering the MLS as an ideal dispersion and the matrix as a system with concentration dependent crystallinity.","abstract_html":"The barrier properties of polymers are a significant factor in determining the shelf or device lifetime in polymer packaging. Nanocomposites developed from the dispersion of nanometer thick platelets into a host polymer matrix have shown much promise. The magnitude of the benefit on permeability has been different depending on the polymer investigated or the degree of dispersion of the platelet in the polymer. In this dissertation, the effect of density changes in the bulk and at the polymer-platelet interface on permeability of polymer nanocomposites is investigated. Nanocomposites of nylon, PET, and PEN were processed by extrusion. Montmorillonite layered silicate (MLS) in a range of concentrations from 1 to 5% was blended with all three resins. Dispersion of the MLS in the matrix was investigated by using one or a combination of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Variation in bulk density via crystallization was analyzed using differential scanning calorimetry (DSC) and polarized optical microscopy. Interfacial densification was investigated using force modulation atomic force microscopy (AFM) and ellipsometry. Mechanical properties are reported. Permeability of all films was measured in an in-house built permeability measurement system. The effect of polymer orientation and induced defects on permeability was investigated using biaxially stretched, small and large cycle fatigue samples of PET and nylon nanocomposites. The effect of annealing in nylon and nanocomposites was also investigated. The measured permeability was compared to predicted permeability by considering the MLS as an ideal dispersion and the matrix as a system with concentration dependent crystallinity.","abstract_has_math":false,"creators":["Sahu, Laxmi Kumari"],"institution":"University of North Texas","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":["D'Souza, Nandika Anne, 1967-","Brostow, Witold, 1934-","Bouanani, Mohamed El","Choi, Tae-Youl"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2007,"date_issued":"2007-05","date_published":"2007-05","updated_at":"2026-07-24T05:34:52Z","subjects":["nanocomposites","permeability","AFM","interfaces","nylon","Polymeric composites -- Permeability.","Nanostructured materials -- Permeability."],"languages":["English"],"rights":["Public","Copyright","Sahu, Laxmi Kumari","Copyright is held by the author, unless otherwise noted. All rights reserved."],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["oclc: 180697535","https://digital.library.unt.edu/ark:/67531/metadc3619/","ark: ark:/67531/metadc3619"],"render_values":[{"text":"oclc: 180697535","href":null,"code":true},{"text":"https://digital.library.unt.edu/ark:/67531/metadc3619/","href":"https://digital.library.unt.edu/ark:/67531/metadc3619/","code":true},{"text":"ark: ark:/67531/metadc3619","href":null,"code":true}]}]},"links":{"outbound_url":"https://doi.org/10.12794/metadc3619","outbound_label":"DOI","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["D'Souza, Nandika Anne, 1967-","Brostow, Witold, 1934-","Bouanani, Mohamed El","Choi, Tae-Youl"]},{"key":"dc:creator","label":"Author","values":["Sahu, Laxmi Kumari"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2007-05"]},{"key":"dc:publisher","label":"Institution","values":["University of North Texas"]},{"key":"dc:type","label":"Dc Type","values":["Thesis or Dissertation"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["nanocomposites","permeability","AFM","interfaces","nylon","Polymeric composites -- Permeability.","Nanostructured materials -- Permeability."]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["Public","Copyright","Sahu, Laxmi Kumari","Copyright is held by the author, unless otherwise noted. 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Nanocomposites of nylon, PET, and PEN were processed by extrusion. Montmorillonite layered silicate (MLS) in a range of concentrations from 1 to 5% was blended with all three resins. Dispersion of the MLS in the matrix was investigated by using one or a combination of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Variation in bulk density via crystallization was analyzed using differential scanning calorimetry (DSC) and polarized optical microscopy. Interfacial densification was investigated using force modulation atomic force microscopy (AFM) and ellipsometry. Mechanical properties are reported. Permeability of all films was measured in an in-house built permeability measurement system. The effect of polymer orientation and induced defects on permeability was investigated using biaxially stretched, small and large cycle fatigue samples of PET and nylon nanocomposites. The effect of annealing in nylon and nanocomposites was also investigated. The measured permeability was compared to predicted permeability by considering the MLS as an ideal dispersion and the matrix as a system with concentration dependent crystallinity."]},{"key":"dc:format","label":"Dc Format","values":["Text"]},{"key":"dc:title","label":"Title","values":["Bulk and Interfacial Effects on Density in Polymer Nanocomposites"]}]}],"canonical_facts":{"dc:contributor":["D'Souza, Nandika Anne, 1967-","Brostow, Witold, 1934-","Bouanani, Mohamed El","Choi, Tae-Youl"],"dc:creator":["Sahu, Laxmi Kumari"],"dc:date":["2007-05"],"dc:description":["The barrier properties of polymers are a significant factor in determining the shelf or device lifetime in polymer packaging. Nanocomposites developed from the dispersion of nanometer thick platelets into a host polymer matrix have shown much promise. The magnitude of the benefit on permeability has been different depending on the polymer investigated or the degree of dispersion of the platelet in the polymer. In this dissertation, the effect of density changes in the bulk and at the polymer-platelet interface on permeability of polymer nanocomposites is investigated. Nanocomposites of nylon, PET, and PEN were processed by extrusion. Montmorillonite layered silicate (MLS) in a range of concentrations from 1 to 5% was blended with all three resins. Dispersion of the MLS in the matrix was investigated by using one or a combination of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Variation in bulk density via crystallization was analyzed using differential scanning calorimetry (DSC) and polarized optical microscopy. Interfacial densification was investigated using force modulation atomic force microscopy (AFM) and ellipsometry. Mechanical properties are reported. Permeability of all films was measured in an in-house built permeability measurement system. The effect of polymer orientation and induced defects on permeability was investigated using biaxially stretched, small and large cycle fatigue samples of PET and nylon nanocomposites. The effect of annealing in nylon and nanocomposites was also investigated. The measured permeability was compared to predicted permeability by considering the MLS as an ideal dispersion and the matrix as a system with concentration dependent crystallinity."],"dc:format":["Text"],"dc:identifier":["oclc: 180697535","doi: 10.12794/metadc3619","https://digital.library.unt.edu/ark:/67531/metadc3619/","ark: ark:/67531/metadc3619"],"dc:language":["English"],"dc:publisher":["University of North Texas"],"dc:rights":["Public","Copyright","Sahu, Laxmi Kumari","Copyright is held by the author, unless otherwise noted. All rights reserved."],"dc:subject":["nanocomposites","permeability","AFM","interfaces","nylon","Polymeric composites -- Permeability.","Nanostructured materials -- Permeability."],"dc:title":["Bulk and Interfacial Effects on Density in Polymer Nanocomposites"],"dc:type":["Thesis or Dissertation"]},"updated_at":"2026-07-24T05:34:52Z"}