Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Synthesis of composite filling materials for non-scratch paints and coatings(01. Izmir Institute of Technology, 2024) Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyModern boyalar ve kaplamaların mekanik ve fiziksel özelliklerinin geliştirilmesi, otomotiv, inşaat ve denizcilik gibi belirli endüstriyel uygulamalar için oldukça önemlidir. Bu araştırma, dayanıklılığı ve çizilme direncini artırmayı hedefleyen, boya ve kaplamalarda kullanılmak üzere silika (SiO₂) ve bor-silika kompozitleri (Boron-SiO₂) içeren kompozit dolgu malzemelerinin geliştirilmesine odaklanmaktadır. Çalışma, bu dolguların diğer katkı maddeleriyle birlikte koruyucu kaplamaların mekanik ve işlevsel özelliklerini nasıl geliştirebileceğini incelemektedir. Silika nanoparçacıklarının iyi bilinen kimyasal stabilitesi, sertliği ve yüksek yüzey alanından yola çıkarak, bu çalışmada kullanılan üretim tekniği Stöber sentez yöntemidir. Bu teknik, partikül boyutu, morfolojisi ve dağılımı üzerinde hassas kontrol sağlar ve kaplama özelliklerinin yüksek bir doğrulukla ayarlanmasına olanak tanır. Ayrıca, boyalar/kaplamalar için çizilme direncini daha da geliştirmek amacıyla Boron-SiO₂ kompozitlerinin sentezi gerçekleştirilmiştir. Silika matrisine bor eklenmesi, malzemenin mekanik dayanımını ve dayanıklılığını artırmış, böylece onu koruyucu uygulamalar için son derece uygun hale getirmiştir. Boron-SiO₂ parçacıklarının özelliklerini optimize etmek için kontrollü içerik ekleme yöntemleri dahil olmak üzere çeşitli sentez teknikleri incelenmiştir. Elde edilen kompozit nanoparçacıklar, SEM, STEM, TEM, FTIR ve ICP-MS gibi karakterizasyon teknikleriyle birlikte parçacık yapısını incelemek için ek testlere tabi tutulmuştur. Çizilme direnci performans testleri, Boron-SiO₂ kompozitleri ile doldurulmuş kaplamaların, üretim yöntemine bağlı olarak geleneksel silika dolgulu kaplamalara göre önemli ölçüde daha iyi performans gösterdiğini ortaya koymuştur.Master Thesis Synthesis of Carbon-Based Flexible Temperature-Controlled Semiconductive Composites(01. Izmir Institute of Technology, 2024) Gündüz, Esra Sıla; Polat, Hürriyet; Polat, Mehmet; Polat, Mehmet; Polat, Hürriyet; 04.01. Department of Chemistry; 03.02. Department of Chemical Engineering; 01. Izmir Institute of Technology; 03. Faculty of Engineering; 04. Faculty of ScienceGünümüzde, yarı iletken polimer matrisli kompozitler ve kullanım alanları araştırmacıların ilgisini çekmektedir. Ayarlanabilir sıcaklık profillerine sahip yarı iletken esnek polimer matrisli kompozitler, robotik, havacılık ve enerji sektörlerinde kullanım alanı bulmaktadır. Ancak karbon nanotüpler, grafen veya metal nanopartiküller gibi pahalı iletken fazlarlara duyulan ihtiyaç nedeniyle üretim maliyeti yüksektir. Bu çalışma, bu tür kompozitlerin üretimi için polidimetilsiloksan matrisinde karbon siyahı ve doğal grafit gibi ucuz iletken malzemelerin kullanılmasını amaçlamaktadır. Kompozitler 'Çözelti karıştırma' yöntemiyle (%10 ila %35 metanolde) hazırlandı ve dağılabilirlik, elektriksel iletkenlik, termal tepki ve mekanik ve morfolojik özellikler açısından test edildi. Bu substratların yüzeylerinin ıslanmayan, düşük enerjili yüzeyler (Fowke teorisine göre 26 J/m2) olduğu bulundu; bu nedenle parçacıklar daha yüksek konsantrasyonlarda (>%30) topaklanma eğilimliydiler. Aglomerasyonun olumsuz sonuçlarını ortadan kaldırmak için yüzey aktif madde ilavesi kullanıldı. Karbon içeriğinin ayarlanması iletkenliği 0 ile 10,79 S/m arasında modüle edilmesini sağlamıştır. 3,17 S/m iletkenliğe sahip tipik bir kompozit, 30 V yük altında 49,7°C yüzey sıcaklığı göstermiştir. PDMS ile karşılaştırıldığında kompozitlerin mekanik özellikler olumluydu; optimum iletkenliğe ve sıcaklık tepkisine sahip bir kompozit, çekme mukavemetinde %50'lik bir düşüşe rağmen elastik modülde %97,8 ve yırtılma mukavemetinde %197 artış gösterdi. Çalışma, istenen sıcaklık profillerine sahip yarı iletken esnek kompozitlerin üretiminde önemli ekonomik potansiyelin altını çiziyor.Master Thesis Development of Doxorubicin-Loaded Liposomes Self-Assembled With Polysaccharides for Breast Cancer Therapy(01. Izmir Institute of Technology, 2023) Kılıç Özdemir, Sevgi; Polat, Hürriyet; Kılıç Özdemir, Sevgi; Polat, Hürriyet; 04.01. Department of Chemistry; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyThis thesis aimed to develop Tariquidar and Doxorubicin-loaded liposomes decorated by Fucoidan coating for breast cancer treatment. Fucoidan is a negatively charged polysaccharide with a special affinity to p-selectins expressed on MDA-MB-231 breast cancer cells and, at the same time, possesses anti-cancer activity. Different liposomes were prepared by extrusion method from the DSPC, Cholesterol, and cationic lipid DSTAP mixtures for coating negatively charged Fucoidan. The most stable liposomes with a size of 200 nm were obtained at a molar ratio of DSPC/Cholesterol/DSTAP:55/30/15, exhibiting a zeta potential above +30 mV. Tariquidar was encapsulated into the liposome bilayer by passive loading, and Doxorubicin into the core of the liposome by active loading. In the final step, liposomes were coated with Fucoidan by electrostatic interaction. Tariquidar loading was determined by UV-Vis spectrophotometry, indicating an optimum TRQ/Lipid molar ratio of 0.012 with encapsulation and loading efficiencies of 50% and 20%, respectively. Fluorescence spectrophotometry determined Doxorubicin loading, showing insignificant encapsulation efficiency change (exhibiting around 70%) by neither Tariquidar content in the bilayer nor DSTAP% in the formulation. An optimum amount of Fucoidan was determined by incubating the liposomes with varying amounts of fucoidan at different dilutions. Size and zeta potential measurements monitored the coating of liposomes with Fucoidan. Our finding showed that zeta potentials of liposomes go from positive to negative with increasing fucoidan, while no trend was observed in the size of liposomes. However, smaller sizes were observed when incubation was performed in diluted solutions.Master Thesis Use of Snps With Controlled Size & Shape for Enhanced Surface Hydrophobicity & Hardness for Coil Coating Applications(01. Izmir Institute of Technology, 2023) Polat, Mehmet; Polat, Hürriyet; Polat, Mehmet; Polat, Hürriyet; 04.01. Department of Chemistry; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyIncreasing the hardness of surface while improving hydrophobicity simultaneously has important implications in coating applications. The use of nano sized particles for this purpose is an interesting area of research. SNPs with mono and multi size distributions in a wide size range were successfully synthesized using the Stöber Method directly or after proper modifications such as utilizing seed particles as in Stöber growth solutions. The synthesized monosize and bi-modal silica particles were then employed in coating studies. The silica nanoparticles were added to a clear coat without pigments and fillers, followed by the introduction of a pigmented topcoat. The addition of 25% monosize silica nanoparticles led to a contact angle (CA) of 92°, while an equal amount of bi-modal silica particles increased the CA to 106°. Notably, the highest CA value of 116.7° was achieved with a 40% addition of bi-modal silica particles. When measured CA was converted to actual CA by incorporating the roughness parameter, the maximum effective CA was calculated as 140°. In terms of mechanical properties, loading monosize silica nanoparticles up to 35% resulted in a surface hardness of 2H. Further increasing the loading to 45% improved the surface hardness to 3H. While a 40% addition of monosize silica was necessary to achieve a pencil hardness of 3H, 20% addition of bi-modal sample was sufficient. The findings above demonstrate that addition of nanosized silica particles simultaneously improve hardness and surface hydrophobicity and that a bi-modal particle size distribution results in a superior performance compared to mono-modal particle size distribution.Master Thesis Preparation and Characterization of Alumina Powders and Suspensions(01. Izmir Institute of Technology, 2000) Şakar, Aylin M.; Şakar Deliormanlı, Aylin Müyesser; Polat, Hürriyet; Polat, Hürriyet; 04.01. Department of Chemistry; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyThis study involves the preparation of fine alumina powders derived from Bayer gibbsite and also aqueous alumina suspensions by using tri block copolymers. Preparation of alumina powders was performed by decomposition of gibbsite into transition alumina phase followed by controlled transformation to alpha phase. To increase transformation rate.. to a-alumina in transition phase hence influence the nucleation and growth rate of the solid-solid phase transformation ball milling and ultrasonication was applied. Gibbsite was thermally treated at 900°C to reach a transition form of alumina. In some cases a heat treatment at 350 °C was applied to create a network of submicroscopic cracks in the heated gibbsite that may help grinding. Ball milling and ultrasonic treatment before calcination at 1100, 1200 °C and 1450 °C followed these heat treatments. Characterizations of the powders were performed with XRD, FTIR, thermal analysis, density measurements and particle size determinations. According to the XRD patterns, complete transformation to alpha form occurred in powders previously heat treated at 900°C, mechanical treated and then cfllcined at 1200 °C in 8 hours and 1450 °C in 2 hours. Powders that were calcined at 1100 °C and 1200 °C in 1-2 hours contained considerable amount of kappa form together with alpha. The effect of the polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO/PPO/PEO) blockcopolymers on the dispersion behaviour of alumina powder suspensions in water were investigated at <1>.0.125,1.0,14 and 50 vol% solid loadings by rheological and turbidity measurements. To compare the effects of block copolymers with other type of dispersants, measurements of some other well known dispersants were also conducted at 10-7 to 10-3 M. The results indicated that type block copolymers with high EO percentage have a positive effect when they are used with ultrasonic treatment on the agglomerated alumina suspensions. But it was not able to create stable dispersions ll1 the absence of ultrasonic bath application. Turbidity measurements at <1>.0.5 wt% showed that some dispersants gave higher dispersion but the stability was reached after a time period. Ultrasonic treatment created stability but lowered the turbidity values.