Analysis of Thermoplastic Polyimide + Polymer Liquid Crystal Blends Metadata
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- Main Title Analysis of Thermoplastic Polyimide + Polymer Liquid Crystal Blends
Author: Gopalanarayanan, BhaskarCreator Type: Personal
Chair: Brostow, Witold, 1934-Contributor Type: PersonalContributor Info: Major Professor
Committee Member: Reidy, Richard F.Contributor Type: Personal
Committee Member: D’Souza, Nandika Anne, 1967-Contributor Type: Personal
Committee Member: Watt, George WilliamContributor Type: Personal
Committee Member: Kozak, Michael R.Contributor Type: Personal
Name: University of North TexasPlace of Publication: Denton, Texas
- Creation: 1998-05
- Content Description: Thermoplastic polyimides (TPIs) exhibit high glass transition temperatures (Tgs), which make them useful in high performance applications. Amorphous and semicrystalline TPIs show sub-Tg relaxations, which can aid in improving strength characteristics through energy absorption. The a relaxation of both types of TPIs indicates a cooperative nature. The semicrystalline TPI shows thermo-irreversible cold crystallization phenomenon. The polymer liquid crystal (PLC) used in the blends is thermotropic and with longitudinal molecular structure. The small heat capacity change (ACP) associated with the glass transition indicates the PLC to be rigid rod in nature. The PLC shows a small endotherm associated with the melting. The addition of PLC to the semicrystalline TPI does not significantly affect the Tg or the melting point (Tm). The cold crystallization temperature (Tc) increases with the addition of the PLC, indicating channeling phenomenon. The addition of PLC also causes a negative deviation of the ACP, which is another evidence for channeling. The TPI, PLC and their blends show high thermal stability. The semicrystalline TPI absorbs moisture; this effect decreases with the addition of the PLC. The absorbed moisture does not show any effect on the degradation. The addition of PLC beyond 30 wt.% does not result in an improvement of properties. The amorphous TPI + PLC blends also show the negative deviation of ACP from linearity with composition. The addition of PLC causes a decrease in the thermal conductivity in the transverse direction to the PLC orientation. The thermomechanical analysis indicates isotropic expansivity for the amorphous TPI and a small anisotropy for the semicrystalline TPI. The PLC shows large anisotropy in expansivity. Even 5 wt. % concentration of PLC in the blend induces considerable anisotropy in the expansivity. Thus, blends show controllable expansivity through PLC concentration. Amorphous TPI + PLC blends also show excellent film formability. The amorphous TPI blends show good potential for applications requiring high thermal stability, controlled expansivity and good film formability.
- Physical Description: x, 142 leaves : ill.
- Keyword: thermoplastic polyimide
- Keyword: polymer liquid crystal blends
- Library of Congress Subject Headings: Polymer liquid crystals.
- Library of Congress Subject Headings: Polyimides.
- Library of Congress Subject Headings: Thermoplastics.
Name: UNT Theses and DissertationsCode: UNTETD
Name: UNT LibrariesCode: UNT
- Rights Access: public
- Rights License: copyright
- Rights Statement: Copyright is held by the author, unless otherwise noted. All rights reserved.
- Rights Holder: Gopalanarayanan, Bhaskar
- Thesis or Dissertation
- Call Number: 379 N81d no.4629
- Accession or Local Control No: 1002659233-gopalanarayanan
- UNT Catalog No.: b2097081
- Archival Resource Key: ark:/67531/metadc279285
- Degree Level: Doctoral
- Degree Grantor: University of North Texas
- Degree Name: Doctor of Philosophy
- Academic Department: Department of Materials Science
- Degree Discipline: Materials Science