Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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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, MetinThe 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 Synthesis of Silica Nano Particles With Custom-Made Morphology for Controlled Drug Delivery(Izmir Institute of Technology, 2012) Siretli, Çağrı; Polat, MehmetThe purpose was to have nanosized particles with low energy perimeters which function as non-reacting transporters for targeted delivery along with high energy sites inside the pores to achieve controlled release of specialized chemicals. Surfactants were used in combination with both base and acid catalyzed methods to achive desired structural properties and the characterization studies such as SEM, TEM, FTIR, BET surface area, pore size, size and zeta potential measurements were conducted. The effect of surfactants on mesoporous silica production changed depending on the type of methods. In the case of base catalysed method in alcohol, formation of stabilized emulsions with different sizes and their effect on the size and shape of silica particles was proposed. The effect of surfactants was attributed to their effect on a) the emulsification process and b) silica-silica and silica-surfactant interactions involved. In the case of base catalysed silica production in water, however, surfactant micelles were used as templates to produce pores. The effect of surfactant type and concentration was attributed to their effect on the CMC, micelle shape and size. Rod-like (~400 nm) at high and spherical (~200 nm) particles at low concentrations were synthesized. Here the surface area of ~1000 m2/g and average pore size of ~3 nm were obtained. Carbonization of these materials were performed to obtain nanosized silica particles with low energy perimeters successfully. Acid catalysed silica production in water was similar. Rod-like (600-800 nm) and cubic (800-1000 nm) nanoparticles were produced. These particles exhibited lower surface area of ~700 m2/g and larger pore size of ~5 nm.