Date of Award

12-2010

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Chemistry

Advisor

Smith, Dennis W

Committee Member

Smith , Dennis W

Committee Member

Smith , Rhett C

Committee Member

Creager , Stephen E

Committee Member

Pennington , William T

Committee Member

Hoffman , Wesley P

Abstract

Carbon fiber polymer composites have attracted worldwide interest in sporting goods and aerospace industries due to their excellent specific strength, stiffness and lightweight. The replacement of solution-spinning process by melt-spinning process is one of the major approaches to make cost effective carbon fiber. In recent years, researchers have explored the possibilities to synthesize melt processable carbon fiber precursors, but their thermal stabilization is still a challenge. The goal for this research project is to prepare melt processable carbon fiber precursors which have the capability of thermal stabilization. Acrylonitrile/1-vinylimidazole (AN/VIM) copolymers containing various mol% of VIM were synthesized by free radical solution polymerization. The copolymers were characterized by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy, 1H-NMR spectroscopy, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). 82/18 mol percent of AN/VIM copolymer based carbon fiber precursor was processed by melt spinning at 192 °C and thermal stabilization of the melt-spun fiber was achieved by heating in air at 250 °C for 5 hrs. The change of fiber structure during stabilization process was confirmed with ATR-IR spectra. Tan Delta value of the stabilized fiber is 0.17, which is much lower than that of as-spun fiber, about 2.12. The oxidized fiber (250 °C / 5 h) did keep its shape after carbonization at 1000 °C for 2 h, which indicates that poly (acrylonitrile-co-1-vinylimidazole) melt-spun fiber after thermal stabilization can be carbonized. A novel dispersion polymerization of poly (acrylonitrile - co -1- vinylimidazole) by using small amount of protonated copolymer itself as a stabilizer was also introduced in this study.
Poly (acrylonitrile - co -1-vinylimidazolium tetrafluoroborate) and poly (acrylonitrile - co -1-vinylimidazolium hexafluorophosphate) were synthesized for gas separation membranes. Terpolymers of methyl methacrylate, methyl acrylate and furfuryl methacrylate (MMA/MA/FMA) were synthesized successfully by solution polymerization and emulsion polymerization and were characterized by 1H NMR, ATR-IR and DSC. The thermo-reversible property of MMA/MA/FMA and BMI cross-linked polymer was confirmed by solubility test. The MMA/MA/FMA and BMI cross-linked polymer emulsion can be applied for making thermally re-moldable carbon fiber composite.

Included in

Chemistry Commons

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