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The effect of the interphase/interface region on creep and creep rupture of thermoplastic composites

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dc.contributor.authorChang, Yeou Shinen
dc.contributor.committeememberDillard, David A.en
dc.contributor.committeememberBaird, Donald G.en
dc.contributor.committeememberLoos, Alfred C.en
dc.contributor.committeememberStinchcomb, Wayne W.en
dc.contributor.committeememberWard, Thomas C.en
dc.contributor.departmentMaterials Engineering Scienceen
dc.date.accessioned2014-03-14T21:14:22Zen
dc.date.adate2008-06-06en
dc.date.available2014-03-14T21:14:22Zen
dc.date.issued1992-05-01en
dc.date.rdate2008-06-06en
dc.date.sdate2008-06-06en
dc.description.abstractThe effect of the interphase/interface region on the static mechanical properties, creep and creep rupture behavior of thermoplastic (J2) composites was investigated. The mechanical properties of the J2 composites were altered by systematic changes in fiber surface chemistry. Four fiber systems were used including the AU4, AS4(1) & (2), and AS4CGP fibers. (AS4(1) and AS4(2) represent different batch numbers.) Surface energies and chemistry of carbon fibers were examined using the Dynamic Contact Angle (DCA) method and X-ray Photoelectron Spectroscopy (XPS), respectively. The meso indentation technique was used to measure the interfacial shear strengths (ISS) of the composites. For the same batch of the composites, the ISS ratios for AS4(2)/J2 to AU4/J2 and AS4CGP/J2 to AU4/J2 were 1.22 and 1.24, respectively. The mechanical properties of these composites in the fiber direction were insensitive to the ISS. The transverse and shear moduli of the J2 composites were also not affected by the ISS. The static strengths, in general, ordered themselves from strong to weak as follows: AS4(2)/J2> AS4CGP/J2> AU4/J2. However, the creep rupture strength revealed a different ordering: AS4CGP/J2> AS4(2)/J2> AU4/J2. This suggests that static mechanical properties may not be a good indicator for long term mechanical performance. Experimental results showed that the interphase/interface region did not affect the degradation rates of the creep rupture strength of the J2 composites. DMA creep tests were performed at elevated temperatures for J2 composites. A master curve of each composite was generated. The shift factors obeyed the Arrhenius type equation. The activation energies of composites were approximately the same. The creep response of the AU4/J2, AS4(2)/J2, and AS4CGP/J2 composites were not dependent upon the ISS. Severe delaminations were observed in the AS4(1)/Jd2 composite laminates. The ([±45/90₂]<sub>s</sub>) laminate tensile strength of AS4(1)/J2 composite was less than that of AS4(2)/J2 and AS4CGP/J2 composite. The creep rupture strength of the AS4(1)/J2 composite laminates degraded about two times faster than that of the other three composite systems.en
dc.description.degreePh. D.en
dc.format.extentxi, 154 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-06062008-170854en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-06062008-170854/en
dc.identifier.urihttp://hdl.handle.net/10919/38439en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V856_1992.C526.pdfen
dc.relation.isformatofOCLC# 26248042en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V856 1992.C526en
dc.subject.lcshThermoplastic composites -- Creepen
dc.titleThe effect of the interphase/interface region on creep and creep rupture of thermoplastic compositesen
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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