{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/39571"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/39571","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Crystallization and melting behavior of an aromatic semicrystalline polyimide, LaRC CPI-2","abstract":"Research is presented on the crystallization and melting behavior of an aromatic semi crystalline polyimide known as LaRC CPI - 2 (Langley Research Center Crystalline rolyimide - second generation). This aromatic polyimide, a structural variant of the well known LaRC CPI, is synthesized froml 1,4-bis( 4-aminophenoxy-4' -benzoyl)benzene (1,4-BABB) and 4,4' -oxydiphthalic dianhydride (ODPA). The multiple melting behavior at ca. 334°C and 364°C, characteristic of this polymer, is analyzed and explained. Transmission electron microscopy (TEM), wide angle X-ray diffraction (W AXD), and small angle X-ray scattering (SAXS) studies, in conjunction with differential scanning calorimetry (DSC) analysis, show that the high melting transition results from the melting of lamellae which were melt recrystallized during heating in a DSC. The effects of synthesis and process variables upon the crystallization and melting properties of this polyimide were also studied. The DSC response of LaRC CPI - 2 films and powders of varying molecular weight are compared and contrasted. Powders generally melt at a higher temperature than films of the same molecular weight. The glass transition temperature, T g' of both the powders and films are found to be dependent upon molecular weight. An interpolated value of T g for the infinite molecular weight LaRC CPI - 2 is ca. 234°e. In a study of the development of crystallinity in films during standard thermal imidization, crystallinity was found to initiate off the glass surface very early in the process leaving an amorphous layer at the air surface after the full thermal treatment. LaRC CPI - 2 powder 'types' synthesized in different solvents, dimethylacetamide (DMAc) and m-cresol present with dramatically different melting, melt stability and crystallization properties. Though the chemical architecture and crystal lattice structure are the same, the powders synthesized in DMAc display dual melting transitions at ca. 334°C and 364°C, while the powders from m-cresol melt singularly at ca. 409°C. Rheological analysis, along with annealing data, revealed a higher temperature melt stability in the powders from m-cresol. It is postulated that the differences in the properties of the two powders are the result of differing initial molecular weights and a suppression of a cross-linking ketimine reaction in the polymer produced in m-cresol.","abstract_html":"Research is presented on the crystallization and melting behavior of an aromatic semi crystalline polyimide known as LaRC CPI - 2 (Langley Research Center Crystalline rolyimide - second generation). This aromatic polyimide, a structural variant of the well known LaRC CPI, is synthesized froml 1,4-bis( 4-aminophenoxy-4' -benzoyl)benzene (1,4-BABB) and 4,4' -oxydiphthalic dianhydride (ODPA). The multiple melting behavior at ca. 334°C and 364°C, characteristic of this polymer, is analyzed and explained. Transmission electron microscopy (TEM), wide angle X-ray diffraction (W AXD), and small angle X-ray scattering (SAXS) studies, in conjunction with differential scanning calorimetry (DSC) analysis, show that the high melting transition results from the melting of lamellae which were melt recrystallized during heating in a DSC. The effects of synthesis and process variables upon the crystallization and melting properties of this polyimide were also studied. The DSC response of LaRC CPI - 2 films and powders of varying molecular weight are compared and contrasted. Powders generally melt at a higher temperature than films of the same molecular weight. The glass transition temperature, T g' of both the powders and films are found to be dependent upon molecular weight. An interpolated value of T g for the infinite molecular weight LaRC CPI - 2 is ca. 234°e. In a study of the development of crystallinity in films during standard thermal imidization, crystallinity was found to initiate off the glass surface very early in the process leaving an amorphous layer at the air surface after the full thermal treatment. LaRC CPI - 2 powder 'types' synthesized in different solvents, dimethylacetamide (DMAc) and m-cresol present with dramatically different melting, melt stability and crystallization properties. Though the chemical architecture and crystal lattice structure are the same, the powders synthesized in DMAc display dual melting transitions at ca. 334°C and 364°C, while the powders from m-cresol melt singularly at ca. 409°C. Rheological analysis, along with annealing data, revealed a higher temperature melt stability in the powders from m-cresol. It is postulated that the differences in the properties of the two powders are the result of differing initial molecular weights and a suppression of a cross-linking ketimine reaction in the polymer produced in m-cresol.","abstract_has_math":false,"creators":["Brandom, Donald Keith"],"institution":"Virginia Tech","degree_name":"Ph. D.","degree_level":"doctoral","degree_discipline":"Materials Engineering Science","degree_department":"Materials Engineering Science","school":null,"contributors":[],"advisors":[],"committee_chairs":["Wilkes, Garth L."],"committee_members":["Davis, Richey M.","Marand, Hervé L.","Kander, Ronald G.","McGrath, James E."],"year":1996,"date_issued":"1996-06-05","date_published":"1996-06-05","updated_at":"2026-07-22T22:19:19Z","subjects":["processing","synthesis","LaRC polyimide","crystallization","melting"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-10032007-171904"],"render_values":[{"text":"etd-10032007-171904","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/39571","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Wilkes, Garth L."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Davis, Richey M.","Marand, Hervé L.","Kander, Ronald G.","McGrath, James E."]},{"key":"dc:contributor.department","label":"Department","values":["Materials Engineering Science"]},{"key":"dc:creator","label":"Author","values":["Brandom, Donald Keith"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T21:19:47Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T21:19:47Z","2007-10-03"]},{"key":"dc:date.issued","label":"Date","values":["1996-06-05"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Engineering Science"]},{"key":"thesis:degree_level","label":"Degree Level","values":["doctoral"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph. 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This aromatic polyimide, a structural variant of the well known LaRC CPI, is synthesized froml 1,4-bis( 4-aminophenoxy-4' -benzoyl)benzene (1,4-BABB) and 4,4' -oxydiphthalic dianhydride (ODPA). The multiple melting behavior at ca. 334°C and 364°C, characteristic of this polymer, is analyzed and explained. Transmission electron microscopy (TEM), wide angle X-ray diffraction (W AXD), and small angle X-ray scattering (SAXS) studies, in conjunction with differential scanning calorimetry (DSC) analysis, show that the high melting transition results from the melting of lamellae which were melt recrystallized during heating in a DSC. The effects of synthesis and process variables upon the crystallization and melting properties of this polyimide were also studied. The DSC response of LaRC CPI - 2 films and powders of varying molecular weight are compared and contrasted. Powders generally melt at a higher temperature than films of the same molecular weight. The glass transition temperature, T g' of both the powders and films are found to be dependent upon molecular weight. An interpolated value of T g for the infinite molecular weight LaRC CPI - 2 is ca. 234°e. In a study of the development of crystallinity in films during standard thermal imidization, crystallinity was found to initiate off the glass surface very early in the process leaving an amorphous layer at the air surface after the full thermal treatment. LaRC CPI - 2 powder 'types' synthesized in different solvents, dimethylacetamide (DMAc) and m-cresol present with dramatically different melting, melt stability and crystallization properties. Though the chemical architecture and crystal lattice structure are the same, the powders synthesized in DMAc display dual melting transitions at ca. 334°C and 364°C, while the powders from m-cresol melt singularly at ca. 409°C. Rheological analysis, along with annealing data, revealed a higher temperature melt stability in the powders from m-cresol. It is postulated that the differences in the properties of the two powders are the result of differing initial molecular weights and a suppression of a cross-linking ketimine reaction in the polymer produced in m-cresol."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Ph. D."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["BTD"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Crystallization and melting behavior of an aromatic semicrystalline polyimide, LaRC CPI-2"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Wilkes, Garth L."],"dc:contributor.committeemember":["Davis, Richey M.","Marand, Hervé L.","Kander, Ronald G.","McGrath, James E."],"dc:contributor.department":["Materials Engineering Science"],"dc:creator":["Brandom, Donald Keith"],"dc:date.accessioned":["2014-03-14T21:19:47Z"],"dc:date.available":["2014-03-14T21:19:47Z","2007-10-03"],"dc:date.issued":["1996-06-05"],"dc:description.abstract":["Research is presented on the crystallization and melting behavior of an aromatic semi crystalline polyimide known as LaRC CPI - 2 (Langley Research Center Crystalline rolyimide - second generation). This aromatic polyimide, a structural variant of the well known LaRC CPI, is synthesized froml 1,4-bis( 4-aminophenoxy-4' -benzoyl)benzene (1,4-BABB) and 4,4' -oxydiphthalic dianhydride (ODPA). The multiple melting behavior at ca. 334°C and 364°C, characteristic of this polymer, is analyzed and explained. Transmission electron microscopy (TEM), wide angle X-ray diffraction (W AXD), and small angle X-ray scattering (SAXS) studies, in conjunction with differential scanning calorimetry (DSC) analysis, show that the high melting transition results from the melting of lamellae which were melt recrystallized during heating in a DSC. The effects of synthesis and process variables upon the crystallization and melting properties of this polyimide were also studied. The DSC response of LaRC CPI - 2 films and powders of varying molecular weight are compared and contrasted. Powders generally melt at a higher temperature than films of the same molecular weight. The glass transition temperature, T g' of both the powders and films are found to be dependent upon molecular weight. An interpolated value of T g for the infinite molecular weight LaRC CPI - 2 is ca. 234°e. In a study of the development of crystallinity in films during standard thermal imidization, crystallinity was found to initiate off the glass surface very early in the process leaving an amorphous layer at the air surface after the full thermal treatment. LaRC CPI - 2 powder 'types' synthesized in different solvents, dimethylacetamide (DMAc) and m-cresol present with dramatically different melting, melt stability and crystallization properties. Though the chemical architecture and crystal lattice structure are the same, the powders synthesized in DMAc display dual melting transitions at ca. 334°C and 364°C, while the powders from m-cresol melt singularly at ca. 409°C. Rheological analysis, along with annealing data, revealed a higher temperature melt stability in the powders from m-cresol. It is postulated that the differences in the properties of the two powders are the result of differing initial molecular weights and a suppression of a cross-linking ketimine reaction in the polymer produced in m-cresol."],"dc:description.degree":["Ph. D."],"dc:format.medium":["BTD"],"dc:format.mimetype":["application/pdf"],"dc:identifier.other":["etd-10032007-171904"],"dc:identifier.uri":["http://hdl.handle.net/10919/39571"],"dc:language.iso":["en"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["processing","synthesis","LaRC polyimide","crystallization","melting"],"dc:title":["Crystallization and melting behavior of an aromatic semicrystalline polyimide, LaRC CPI-2"],"dc:type":["Dissertation"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Materials Engineering Science"],"thesis:degree_level":["doctoral"],"thesis:degree_name":["Ph. D."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:19Z"}