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Browsing Agriculture by Subject "Carbon nanotubes"

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    Preparation and characterization of nafion-based nanocomposite membranes for fuel cell applications
    (2010) Cele, Nonhlanhla Precious; Ray, S.S.; Ndwandwe, O.M.
    The Nafion-based nanocomposite membranes with improved properties were prepared by melt-extrusion process at 250C. 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.