Solvent-Induced Crystallization of Poly(ether ether ketone)

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dc.contributor.authorMcPeak, Jennifer Lynneen
dc.contributor.committeechairKander, Ronald G.en
dc.contributor.committeememberDavis, Richey M.en
dc.contributor.committeememberWilkes, Garth L.en
dc.contributor.committeememberLove, Brian J.en
dc.contributor.committeememberWard, Thomas C.en
dc.contributor.departmentMaterials Science and Engineeringen
dc.date.accessioned2014-03-14T20:19:42Zen
dc.date.adate1999-04-11en
dc.date.available2014-03-14T20:19:42Zen
dc.date.issued1999-11-15en
dc.date.rdate2000-04-11en
dc.date.sdate1999-12-03en
dc.description.abstractThe purpose of this study was learn how the diffusion, swelling, and crystallization processes are coupled during solvent-induced crystallization of poly(ether ether ketone) (PEEK). Unoriented amorphous PEEK films were immersed in aprotic organic liquids at ambient temperature and bulk properties or characteristics were monitored as a function of immersion time. The sorption behavior, Tg and Tm° suppression, crystallinity, and dynamic mechanical response were correlated as a function of solvent chemistry and immersion time. The saturation time of methylene chloride, 1,3-dichloropropane, tetrahydrofuran, cyclopentanone, chlorobenzene, toluene, diethyl ketone, and ethylbenzene in amorphous PEEK films were found to range from hours to days depending on the level of polymer-solvent interactions. In-situ isochronal DMA spectra show that the Tg of PEEK was suppressed from 150 ° C to below ambient temperature such that crystallization was kinetically feasible during ambient immersion. In addition, an increase in viscoelastic dispersion was attributed to the presence of crystallinity. From dynamic mass uptake and wide-angle x-ray diffraction (WAXD) results, it was found that the bulk sorption rate was equal to the bulk crystallization rate for all solvent systems that promoted SINC and PEEK exhibited diffusion-limited crystallization, irrespective of the nature of the transport mechanism. In addition, the solvent-induced crystals exhibit preferred orientation as supported by photographic WAXD. A distinct sorption front, observed with scanning electron microscopy, further supports the scenario of diffusion-controlled crystallization and one-dimensional diffusion. Isothermal DMA spectra for THF, cyclopentanone, and chlorobenzene, indicate that, as the solvent diffuses into the films, the stiffness of the polymer decreases at short times, begins to increase, and then reaches a relatively time-independent value. It was determined that the initial decrease in the storage modulus was due to the incredible plasticization of the amorphous phase. When the films contained greater than 60 % of the ultimate crystallinity, the storage modulus was observed to increase as a result of the reinforcing effect of the solvent-induced crystals. WAXD and mass uptake results confirm that the plateau in the storage modulus coincides with the completion of bulk crystallization and saturation of the amorphous phase.en
dc.description.degreePh. D.en
dc.identifier.otheretd-120399-113649en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-120399-113649/en
dc.identifier.urihttp://hdl.handle.net/10919/29905en
dc.publisherVirginia Techen
dc.relation.haspartjlmPhDdone.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectdynamic mechanical analysisen
dc.subjectorganic solventsen
dc.subjectdiffusionen
dc.titleSolvent-Induced Crystallization of Poly(ether ether ketone)en
dc.typeDissertationen
thesis.degree.disciplineMaterials Science and Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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