Title page for ETD etd-07032003-103831

Type of Document Master's Thesis
Author Krych, Wojtek S
Author's Email Address wkrych@vt.edu
URN etd-07032003-103831
Title Fabrication and Gas Permeation Studies on Polyimide/Layered-Aluminum Phosphate Nanocomposite Membranes
Degree Master of Science
Department Chemical Engineering
Advisory Committee
Advisor Name Title
Marand, Eva Committee Chair
Davis, Richey M. Committee Member
Saraf, Ravi F. Committee Member
  • Gas Separations
  • Nanocomposite Materials
  • Polyimide
  • Aluminum Phosphate
Date of Defense 2003-07-01
Availability restricted
Polymer – clay nanocomposites have improved thermal, mechanical, and barrier properties when compared with the pure polymer. The objective of this study was to examine if gas separation performance could be improved by introducing a layered nanopourous aluminum phosphate with a large aspect ratio into a polymeric matrix. The aluminum phosphate has eight membered rings, which could potentially serve as a size selective medium. A hexafluorinated polyimide, 6FDA-6FpDA-8%-DABA, was used as the polymeric matrix. The polyimide and the aluminum phosphate were synthesized separately according to well documented procedures. The two materials were blended and fabricated into nanocomposite membranes. The effect of mixing temperature and percentage of layered aluminum phosphate added to the polymer on the permeation properties were examined. These factors had a direct effect on the degree of intercalation and exfoliation of the nanocomposite structure. Transmission FTIR, TEM, DMTA, and X-ray diffraction were used to characterize the morphology, structure, and composition of these nanocomposite films. The permeation properties of the nanocomposite membranes were evaluated using pure gases (He, O2, N2, CH4, CO2) at 35°C and a feed pressure of 4 atm. In general, the permeability decreased and the selectivity coefficients increased when adding 10 wt% aluminum phosphate to the polyimide. Furthermore, the membranes showed size selectivity, consistent with the pore size in the layered aluminum phosphate.
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