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Optimization of Polymer-based Nanocomposites for High Energy Density Applications

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dc.contributor.advisor Ounaies, Zoubeida en_US
dc.creator Barhoumi Ep Meddeb, Amira en_US
dc.date.accessioned 2012-07-16T15:58:53Z en_US
dc.date.accessioned 2012-07-16T20:27:14Z
dc.date.available 2012-07-16T15:58:53Z en_US
dc.date.available 2012-07-16T20:27:14Z
dc.date.created 2012-05 en_US
dc.date.issued 2012-07-16 en_US
dc.date.submitted May 2012 en_US
dc.identifier.uri http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-11225 en_US
dc.description.abstract Monolithic 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_US
dc.format.mimetype application/pdf en_US
dc.language.iso en_US en_US
dc.subject Polymer nanocomposites en_US
dc.subject nanodielectrics en_US
dc.subject energy density en_US
dc.subject dielectric properties en_US
dc.subject high aspect ratio particles en_US
dc.title Optimization of Polymer-based Nanocomposites for High Energy Density Applications en_US
dc.type Thesis en
thesis.degree.department Aerospace Engineering en_US
thesis.degree.discipline Aerospace Engineering en_US
thesis.degree.grantor Texas A&M University en_US
thesis.degree.name Doctor of Philosophy en_US
thesis.degree.level Doctoral en_US
dc.contributor.committeeMember Huff, Gregory en_US
dc.contributor.committeeMember Lagoudas, Dimitris C. en_US
dc.contributor.committeeMember Yu, Choongho en_US
dc.type.genre thesis en_US
dc.type.material text en_US

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