Thesis
An investigation of dielectric properties in three-phase polymer composites for sensing and charge storage applications
Washington State University
Master of Science (MS), Washington State University
12/2018
DOI:
https://doi.org/10.7273/000003958
Handle:
https://hdl.handle.net/2376/122297
Abstract
Electronic devices in today's marketplace are getting smaller and smaller and any large part is getting replaced with a smaller more sensitive part, due to the scarce space available. Therefore, the demand for material with higher sensitivity and better performance is the topic of research nowadays. This study aims to target the sensitivity of two groups of materials: 1) piezoelectric 3-phase polymer composites with improved voltage sensitivity and 2) percolative 3-phase composites with high permittivity, and low dielectric loss. In the first part of this research project, highly filled lead zirconate titanate (PZT)/thermoplastic polyurethane (TPU) composites were fabricated and foamed, with both CO2-foaming and foaming with expandable microspheres. The studied properties were thermal properties, dielectric properties and morphology and microstructures of the foams. The aim was to effectively decrease the dielectric permittivity of the composites, in order to enhance their voltage permittivity. Permittivity continuously decreased in all foamed composites, up to a maximum of 7.7 times, as the volume expansion increased. Yamada model was expanded for 3-phase materials and used to predict the dielectric permittivity of the resultant composites. The experimental and theoretical values were compared in this research. In the second part of this research, multi-walled carbon nanotube (MWCNT) was added to the TPU/PZT composites, with PZT contents 5-30vol.% and MWCNT contents of 0.05-1vol.%. The addition of the third conductive phase resulted in effective micro-capacitors, scattered in a dielectric medium. MWCNT and PZT both can be used as dielectric fillers, however, they both have some disadvantages in the absence of the other filler. Combining the two fillers increases the permittivity of the composites and blocks the contact between MWCNT particles, addressing both materials' shortcomings. The great performance of these new materials in their respectable applications opens up new applications and interest in the field of 3-phased composites with versatile new fillers.
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Details
- Title
- An investigation of dielectric properties in three-phase polymer composites for sensing and charge storage applications
- Creators
- Gayaneh Petrossian
- Contributors
- Amir Ameli (Advisor)
- Awarding Institution
- Washington State University
- Academic Unit
- School of Mechanical and Materials Engineering
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Identifiers
- 99900890804801842
- Language
- English
- Resource Type
- Thesis