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dc.contributor.advisorOunaies, Zoubeida
dc.creatorBarhoumi Ep Meddeb, Amira
dc.date.accessioned2012-07-16T15:58:53Z
dc.date.accessioned2012-07-16T20:27:14Z
dc.date.available2012-07-16T15:58:53Z
dc.date.available2012-07-16T20:27:14Z
dc.date.created2012-05
dc.date.issued2012-07-16
dc.date.submittedMay 2012
dc.identifier.urihttp://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11225
dc.description.abstractMonolithic materials are not meeting the increasing demand for flexible, lightweight and compact high energy density dielectrics. This limitation in performance is due to the trade-off between dielectric constant and dielectric breakdown. Insulating polymers are of interest owing to their high inherent electrical resistance, low dielectric loss, flexibility, light weight, and low cost; however, capacitors produced with dielectric polymers are limited to an energy density of ~1-2 J/cc. Polymer nanocomposites, i.e., high dielectric particles embedded into a high dielectric breakdown polymer, are promising candidates to overcome the limitations of monolithic materials for energy storage applications. The main objective of this dissertation is to simultaneously increase the dielectric permittivity and dielectric breakdown without increasing the loss, resulting in a significant enhancement in the energy density over the unmodified polymer. The key is maintaining a low volume content to ensure a high inter-particle distance, effectively minimizing the effect of local field on the composite's dielectric breakdown. The first step is studying the particle size and aspect ratio effects on the dielectric properties to ensure a judicious choice in order to obtain the highest enhancement. The best results, as a combination of dielectric constant, loss and dielectric breakdown, were with the particles with the highest aspect ratio. Further improvement in the dielectric behavior is observed when the nanoparticles surface is chemically tailored to tune transport properties. The particles treatment leads to better dispersion, planar distribution and stronger interaction with the polymer matrix. The planar distribution of the high aspect ratio particles is essential to limit the enhancement of local fields, where minimum local fields result in higher dielectric breakdown in the composite. The most significant improvement in the dielectric properties is achieved with chemically-treated nano TiO2 with an aspect ratio of 14 at a low 4.6 vol% loading, where the energy density increased by 500% compared to pure PVDF. At this loading, simultaneous enhancement in the dielectric constant and dielectric breakdown occurs while the dielectric loss remains in the same range as that of the pristine polymer.en
dc.format.mimetypeapplication/pdf
dc.language.isoen_US
dc.subjectPolymer nanocompositesen
dc.subjectnanodielectricsen
dc.subjectenergy densityen
dc.subjectdielectric propertiesen
dc.subjecthigh aspect ratio particlesen
dc.titleOptimization of Polymer-based Nanocomposites for High Energy Density Applicationsen
dc.typeThesisen
thesis.degree.departmentAerospace Engineeringen
thesis.degree.disciplineAerospace Engineeringen
thesis.degree.grantorTexas A&M Universityen
thesis.degree.nameDoctor of Philosophyen
thesis.degree.levelDoctoralen
dc.contributor.committeeMemberHuff, Gregory
dc.contributor.committeeMemberLagoudas, Dimitris C.
dc.contributor.committeeMemberYu, Choongho
dc.type.genrethesisen
dc.type.materialtexten


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