Melting and crystallization studies in a partially excluding copolymer

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dc.contributor.authorVerma, Ravi Kanten
dc.contributor.committeechairKander, Ronald G.en
dc.contributor.committeememberFaron, Katherine L.en
dc.contributor.committeememberHsiao, Benjamin S.en
dc.contributor.committeememberMarand, Hervé L.en
dc.contributor.committeememberWard, Thomas C.en
dc.contributor.committeememberWilkes, Garth L.en
dc.contributor.departmentMaterials Engineering Scienceen
dc.date.accessioned2014-03-14T21:22:06Zen
dc.date.adate2005-10-24en
dc.date.available2014-03-14T21:22:06Zen
dc.date.issued1994en
dc.date.rdate2005-10-24en
dc.date.sdate2005-10-24en
dc.description.abstractThe crystallization and melting behavior of copolymers (specially of those which partially exclude the and component) has not been well understood. Poly(ether ketone ketone) PEKK is such a partially excluding copolymer in which the crystalline phase tends to exclude one of two similar monads. Previous studies on PEKK have focused on effects of changing overall composition on the melting and crystallization behavior. These studies have demonstrated that PEKK tends to exclude one of two chemically similar monads from the crystalline phase, and the crystallization and melting behavior is affected as a result of this exclusion. However, the effect of changing linear chain architectures on the thermal behavior of such copolymers has not been investigated. In this study, the effect of changing architectures of the linear chain (blockiness) on the crystallization and melting behavior has been studied. The overall composition of the copolymer is maintained at 50% 2nd comonomer, and a series of samples prepared with different block lengths and amounts of branching. The crystallization and melting behavior of these samples is then studied using hot stage optical microscopy, scattering (small and wide angle X-ray scattering) and thermal analysis techniques (differential scanning calorimetry). It has been demonstrated that, upon changing from an alternating to a non-alternating structure, substantial amounts of 224 component are excluded from the crystalline phase and the melting temperature is raised considerably. Further, because of increased amounts of branching which accompanies the change in blockiness, the crystallization kinetics is slowed down. These results have been analyzed in terms of existing theories of copolymer crystallization, and some speculative arguments have been presented on the factors which affect the crystallization mechanism in such partially excluding copolymers. The validity of equilibrium thermodynamics based on the enthalpic approach has been analyzed.en
dc.description.degreePh. D.en
dc.format.extentxi, 110 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-10242005-124125en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-10242005-124125/en
dc.identifier.urihttp://hdl.handle.net/10919/40130en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V856_1994.V477.pdfen
dc.relation.isformatofOCLC# 32771898en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V856 1994.V477en
dc.subject.lcshThermoplasticsen
dc.titleMelting and crystallization studies in a partially excluding copolymeren
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineMaterials Engineering Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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