Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Author: search.filters.author.Tanoğlu, MetinSubject: search.filters.subject.Nanoparticles

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  • Master Thesis
    Effects of Zirconia and Hydroxyapatite Nanoparticles on the Mechanical Properties of the Resin-Based Dental Composites
    (01. Izmir Institute of Technology, 2023) Tunca Taşkıran, Senagül; Tanoğlu, Metin
    The majority of the population suffers from dental caries, one of the most common chronic diseases. Therefore, restoration of teeth is an urgent need. The materials used in restoration are composites prepared by adding inorganic components to the polymeric matrix. However, failure due to fractures and secondary caries is still the main problem. Therefore, studies are continuing to improve the mechanical properties and water sorption and solubility properties of the composite. In this study, effects of zirconia, which improves the mechanical properties, and hydroxyapatite nanoparticles, which are the components of the tooth, on the mechanical properties of the composite were investigated. According to the literature, amounts of additives were determined as 1 and 2 wt.% for zirconia and 3 and 5 wt.% for hydroxyapatite. Nine different composites were prepared by mixing with hand spatulation method and mortar mill. The flexural strength and modulus, compressive strength, depth of cure, water sorption and solubility properties of the composites were investigated. Samples were characterized by using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Zirconia and HA particles significantly improved the flexural and compressive strength of the composites. The highest flexural strength was obtained in the sample containing 5 wt.% hydroxyapatite and 1 wt.% zirconia, with an increase of 58% compared to the control sample. The highest compressive strength was obtained in the sample containing 3 wt.% hydroxyapatite and 2 wt.% zirconia, with an increase of 22% compared to the control sample. Therefore, zirconia and HA nanoparticles have a synergistic effect.
  • Master Thesis
    Tribological Behaviour of Polymer Nanocomposities Containing Tungsten Based Nanoparticles
    (Izmir Institute of Technology, 2007) Karal, Kazım; Tanoğlu, Metin
    The use of nanostructured fillers in epoxy systems has a significant role on the development of thermosetting composites. Recent investigations on inorganic nanoparticles filled polymer composites reveal their significant potential in producing materials with low friction and/or high wear resistance. In the present study, epoxy nanocomposites and fiber reinforced polymer (FRP) composites were prepared with the addition of tungsten based nanostructured particles which are produced by mechanical alloying. The effects of the nanostructured additives on the tribological, mechanical and thermal properties of composite laminates and nanocomposites were investigated. Composite laminates with and without filler were manufactured by using hand lay-up technique and cured under compression. It was found that tungsten based particle loading has no significant effect on the flexural properties of the nanocomposites and the composite laminates, and the tensile properties of the nanocomposites. It was found that while the addition of 3 wt. % of nanoparticles increases the hardness values, it significantly improves the wear resistance of nanocomposites. Furthermore, the significant improvement on the wear resistance was observed with the addition of 3 wt. % W-SiC-C (24h mechanical milling) powder onto the surface of fiber reinforced epoxy. The worn surfaces were examined with scanning electron microscopy (SEM) and the results revealed that wear mechanisms are altered due to the presence of nanoparticles in the matrix. Differential scanning calorimetry (DSC) results showed that nanoparticles have no significant effect on glass transition temperatures (Tg) of nanocomposites. Incorporation of nanoparticles increased the thermo mechanical properties of nanocomposites and composite laminates; including the storage and loss modulus and Tg.
  • Master Thesis
    Development of Liquid Armor Materials and Rheological Behavior of Shear Thickening Fluids (stfs)
    (Izmir Institute of Technology, 2011) Erdoğan, Taner; Tanoğlu, Metin
    Colloidal dispersions have been extensively used in many industrial applications such as cosmetic, paint, cement, lubricant and ceramic. Shear thickening is non- Newtonian flow behavior often observed in concentrated colloidal dispersions as an increase in viscosity with increasing shear rate or applied stress. Shear thickening fluids (STFs) exhibit fluid and solid-like properties depending on the shear rate and thus can be used in a variety of applications. In the present study, STFs have been synthesized with various weight fractions of silica nanoparticles in polyethylene glycol (PEG)/ethyl alcohol by mechanical mixing method. The steady and dynamic rheological behavior of shear thickening fluids (STFs) was investigated with rheometer. STFs thermal properties were investigated through thermogravimetric analysis. STFs have been used to improve the performance of Kevlar woven fabrics for protective applications in ballistic and stab. STFs/Kevlar fabric composites have been prepared with different impregnation techniques to evaluate the effects of the STFs. The ballistic performance and stab resistance of STFs impregnated Kevlar fabrics were investigated. Rheological measurements revealed the shear thickening effect of silica nanoparticles/PEG systems depending on the shear rate. In dynamic experiments, the strain thickening behavior was found at critical combination of strain amplitude and frequency. The viscous G modulus values were found to be greater than the elastic G modulus. The elastic G and the viscous G modulus values were found to increase when the strain amplitude is kept constant and frequency is increased. The same strain thickening behavior was also found when the frequency was kept constant and the strain amplitude was increased. The puncture resistance of STFs/Kevlar fabric composites exhibited significant improvements as compared to the neat Kevlar targets. Based on the SEM results, STFs were uniformly impregnated over the entire surface on the Kevlar fabric and Kevlar fabrics completely coated with STFs. The ballistic test results revealed STF/Kevlar fabric composites have potential to obtain liquid armor materials.