Preparation and characterization of nafion-based nanocomposite membranes for fuel cell applications
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Date
2010
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Abstract
The Nafion-based nanocomposite membranes with improved properties were
prepared by melt-extrusion process at 250C. The compression molding was then
used for the preparation of thin films of about 0.1–0.3 mm. Carbon nanotubes (CNTs)
were used as nanofiller to improve Nafion properties. CNTs were chemically treated
with nitric acid and hexadecaylamine before incorporation into Nafion. Transmission
electron microscopy showed that chemical treatment did not cause any damage to the
tubes. Differently treated tubes were incorporated into Nafion in different loadings.
CNTs containing Nafion nanocomposite membranes showed significant improvement
in thermal stability. Nitric acid treated CNTs (oCNTs) containing Nafion membranes
showed excellent thermo-mechanical properties. A balance in water uptake and
proton conductivity was observed with Nafion/oCNTs (1wt %) nanocomposite
membrane.
Methyl tallow bis(2-hydroxylethyl) quaternary ammonium salt modified
montmorillonite, commercially known as Cloisite®30B (C30B), was also used as
nanofiller to reduce methanol permeability of Nafion membrane. The content of C30B
was varied from 0.5–2 wt% and its effect on different properties of Nafion was
studied. Thermo-mechanical properties of Nafion were found to improve dramatically
after incorporation of C30B. Methanol permeability of Nafion was decreased after
nanocomposite formation with C30B and the electrical conductivity is independent of
C30B amount.
Titanium dioxide nanotubes (TNTs) were prepared by hydrothermal treatment of
titanium dioxide in presence of potassium hydroxide as a base. TNTs were then used
as nanofiller in different proportions to improve Nafion properties so that it can be
used as a membrane for fuel cell fabrication. Improved thermal stability of Nafion
was observed with incorporation of 0.5 and 2 wt% of TNTs. Methanol permeability
was highly reduced with incorporation of 2 wt% TNTs, indicating possible improved
fuel cell performance.
Description
A thesis submitted to the Faculty of Science and Agriculture University of Zululand
In fulfilment of the requirements for the Degree of Doctor of Philosophy, 2010.
Keywords
Nafion-based nanocomposite membranes, Carbon nanotubes