Some of the material in is restricted to members of the community. By logging in, you may be able to gain additional access to certain collections or items. If you have questions about access or logging in, please use the form on the Contact Page.
To prepare dielectric materials for High Temperature Superconductor (HTS) cables, nanocomposites consisting of Polymethylmethacrylate (PMMA) and Barium Titanate (BTA) nanoparticles have been manufactured and evaluated. The main objective of this research is to enhance the dielectric breakdown strength and reduce the dielectric losses of the nanocomposites. Polymethylmethacrylate (PMMA) with the addition of BTA (5wt.% and 10wt.% ) nanocomposites were fabricated by using two different methods. The breakdown voltage measurements have been conducted under AC, DC and lightning impulse high voltage. The measurements were conducted at both room temperature (293 K) and liquid nitrogen temperature (77 K). The results of the electrical breakdown field measurements of the nanocomposites are compared with those of the base polymer. Fracture surface analysis was carried out with SEM analysis. The difference in the breakdown area due to different modes of voltages applied and effect of the nanoparticles was studied. Mechanical characterization of the resultant nanocomposites was also carried out at both the room temperature (293K) and at cryogenic temperature (77K). The effects of nanoparticles on the electrical and mechanical properties were observed. A marginal increase in the dielectric strength of the nanocomposites was observed for AC conditions at both the temperatures. There was a decrease in the values of nanocomposites for impulse conditions. At cryogenic temperature nanocomposites showed higher dielectric strength when DC voltage was applied. For both the temperatures, dielectric losses increased as the voltage was increased for all the materials studied, except for PMMA/10wt.%BTA nanocomposites at cryogenic temperature, which showed decrease of losses by ~ 70%. An increase of ~12% in Young's modulus and ~ 65% increase in tensile strength of the nanocomposites were observed at cryogenic temperature. It also shows that more material damage was observed under AC breakdown voltage compared to the impulse and DC voltage breakdown cases. Also the material damage was more pronounced at 77 K than that at 293 K.
Tan Delta Losses, Impulse Breakdown, DC Breakdown, AC Breakdown, Barium Titanate, Polymethylmethacrylate (PMMA), Cryogenic Insulation, High Temperature Superconductors (HTS), Nanodielectrics, Mechanical Breakdown, Surface Fracture Analysis, Weibull Plots
Date of Defense
July 6, 2010.
A Thesis submitted to the Department of Industrial and Manufacturing Engineering in partial fulfillment of the requirements for the degree of Master of Science.
Includes bibliographical references.
Zhiyong Richard Liang, Professor Directing Thesis; Horatio Rodrigo, Committee Member; Okenwa Okoli, Committee Member; Mei Zhang, Committee Member.
Florida State University
Use and Reproduction
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them.