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Development of Multi and Double Walled Carbon Nanotubes (cnts) / Vinylester Nanocomposites
(Izmir Institute of Technology, 2008) Tanoğlu, Metin; Tanoğlu, Metin; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
This study focuses on development and characterization of thermosetting resin based nanocomposites containing multi and double walled carbon nanotubes with and without amine functional groups (MWCNT, DWCNTs, MWCNT-NH2 and DWCNTNH2).A novel 3-roll milling technique was conducted to prepare the resin suspensions with carbon nanotubes (CNTs). Rheological measurements performed on the resin suspensions showed that addition of very low contents (0.05, 0.1 and 0.3 wt. %) of MWCNTs and MWCNT-NH2 affected the flow characteristic of the resin, significantly.Further, the curing behavior of a vinylester-polyester hybrid resin suspensions containing 0.3 wt % of MWCNTs and MWCNT-NH2 was intensively studied. It was found that regardless of amine groups, presence of CNTs affected the polymerization of the hybrid matrix resin. Final individual fractional conversion rates of styrene and vinylester monomers were found to be vastly dependent on the type of CNTs. Glass transition temperature (Tg) values of the nanocomposites with MWCNTs and MWCNTNH2 were found to increase with filler content. Moreover, nanocomposites containing MWCNTs and MWCNT-NH2 were found to possess higher tensile strength, elastic modulus as well as fracture toughness and fracture energy as compared to the neat hybrid resin. On the other hand, electrical properties of the nanocomposites were also investigated and it was found that nanocomposites with MWCNTs exhibited the lowest percolation threshold value. In addition, nanocomposites with amino functionalized CNTs were found to exhibit lower electrical conductivity as compared to those with untreated CNTs. Nanocomposites with AC electric field induced aligned CNTs were also prepared. Finally, based on the findings obtained for CNT/ resin suspensions, as a case study, electrically conductive glass fiber reinforced composite laminates were successfully produced, using the CNT modified resin suspensions as matrix material, via Vacuum Assisted Resin Transfer Molding (VARTM) and Resin Transfer Molding (RTM) methods.
Development and Characterization of Whey Based Alpha-Lactalbumin Protein Nanotubes for Food Applications
(Izmir Institute of Technology, 2013) Tarhan, Özgür; Harsa, Hayriye Şebnem; Harsa, Hayriye Şebnem; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Alpha-lactalbumin (α-La) is one of the major proteins in whey. When partially hydrolyzed with protease, it produces nanotubular structures by self-assembly process. The aim of this PhD thesis is to develop and characterize whey based α-La nanotubes. In this study, purification of α-La from whey using ultrafiltration and chromatography, development of protein nanotubes with standard and purified α-La fractions, their characterization by microscopic, optical and spectrophotometric methods, analysis of hydrolysis process, and investigation of these nanotubes in relation to food applications were presented. Lactose was eliminated and proteins were concentrated in whey powder by diafiltration assisted ultrafiltration prior to chromatography. α-La and besides β- lactoglobulin were purified individually from whey protein concentrate with high purity (95–99 %). The obtained protein nanotubes were longer than 100 nm up to few microns with ~20 nm width in bundled, rod and chain-like fashions. Remarkable conformational changes occurred in the protein secondary structure during nanotube formation. Calcium to protein ratio critically affected nanotube formation and stability. Both hydrolysis and nanotube growth triggered gelation, but stiffer gel network was obtained with nanotubes. Viscoelasticity and stiffness were improved by blending with cellulose. As the calcium content increased the transparent appearance of the gels got turbid due to aggregation. α-La nanotubes were stable up to ~ 60 °C. The nanotubular gels entrapped a coloring agent by enhancing transparency. Binding of catechin to nanotubes was occured as reversible with low stability. α-La nanotubes and gels can be used as functional ingredients in food processing involving low and moderate heat treatments.

Phd Degree / Doktora

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