Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
27 results
Search Results
Master Thesis EPDM Kauçuk Bileşiklerinde Si-kerf'in Dolgu Maddesi Olarak Kullanımı: Mekanik ve Termal Özellikler(2025) Aksoy, Özge; Demir, Mustafa Muammer; Gökelma, MertolBu tez çalışmasında, güneş paneli üretiminde oluşan silikon kerf (Si-kerf) atığının, etilen-propilen-dien monomer (EPDM) esaslı kauçuk bileşiklerinde takviye edici dolgu malzemesi olarak kullanılabilirliği araştırılmıştır. Sürdürülebilirlik hedefleri doğrultusunda yapılan bu çalışmada, Si-kerf'in farklı oranlarda kullanıldığı bileşiklerin reolojik davranışları, mekanik özellikleri, termal dayanımları ve yaşlanma sonrası performansları incelenmiştir. ASTM ve SAE J20 standartlarına uygun olarak yürütülen deneysel çalışmalarda, numuneler çekme testi, sertlik, yaşlanma dayanımı, şişme analizi ve çapraz bağ yoğunluğu ölçümleriyle karakterize edilmiştir. Ayrıca, hacimsel şişme yöntemi kullanılarak çapraz bağ yoğunluğu hesaplanmış, Flory-Rehner denklemi ile sayısal değerler elde edilmiştir. SEM ve EDX analizleri, Si-kerf parçacıklarının EPDM matrisi içinde yüzey modifikasyonuna ihtiyaç duymadan iyi dağılabildiğini ve dolgu-polimer etkileşiminin yeterli olduğunu göstermiştir. Elde edilen bulgular, geri kazanılmış silikanın özellikle %10–20 oranlarında kullanıldığında, CB100 referans bileşiği ile yakın hatta üstün mekanik ve termal performans sergilediğini göstermektedir. %20 Si-kerf ve %80 karbon siyahı içeren CB80–Skf20 formülasyonu, çekme dayanımı, çapraz bağ yoğunluğu ve termal yaşlanma performansı açısından en dengeli sonucu vermiştir. Bu çalışma, Si-kerf'in kauçuk endüstrisinde çevreci ve ekonomik bir alternatif olarak değerlendirilebileceğini göstermektedir.Master Thesis Birnessit Tipi Manganez Dioksit (δ-MnO2) Kullanılarak Jeotermal Tuzlu Sulardan Rubidyumun Ayrılmasına Doğru(2025) Akkuş, Özge Sezin; Demir, Mustafa Muammer; Baba, AlperKritik minerallerden rubidyum, fiziksel ve kimyasal özellikleriyle birçok alanda uygulama potansiyeli sunan, yüksek ekonomik değere sahip alkali bir metaldir. Bu yüzden rubidyumun geri kazanımı ile ilgili çalışmalar yoğun ilgi görmektedir. Rubidyumun birincil kaynaklardan elde edilmesindeki çevresel etkiler ve tedarikindeki kesintilere karşı savunmasız oluşu, tuzlu sulardan geri kazanımını alternatif olarak öne çıkarmaktadır. Potansiyel bir rubidyum kaynağı olan jeotermal tuzlu sularda rubidyumun belirlenmesinin ve izole edilmesinin araştırıldığı bu çalışmada, adsorpsiyon yöntemi ve birnessit tipi manganez dioksit (δ-MnO2) adsorbanı kullanılarak rubidyumun sulu çözeltilerden ayrıştırılması incelenmiştir. Rubidyumun ayrılması sürecinde birnessit tipi (sodyum) manganez dioksit, eş çöktürme ve hidrotermal yöntemler kullanılarak sentezlendi. Malzemenin sentezlenmesi ve Na+ iyonlarının liçing yöntemi kullanılarak uzaklaştırılması işlemleri, XRD ve SEM-EDX analizleriyle doğrulandı. Malzeme karakterizasyonu sonrasında, başlangıç konsantrasyonu, sorbent dozu, sorpsiyon sıcaklığı, pH ve temas süresi parametrelerinin etkisi incelenerek malzemenin adsorpsiyon performansı karşılaştırıldı. Sentetik rubidyum çözeltileriyle pH=7, t=30 dk, Co= 10 ppm, m= 10 mg, V=10 mL, T=55oC optimum koşullarında yapılan kesikli adsorpsiyon deneylerinde adsorpsiyon kapasitesi 9,33 mg/g, uzaklaştırma verimliliği %91,21 olarak hesaplandı. Birnessit tipi manganez dioksitin gerçek sistemdeki performansının incelenmesinde Tuzla Jeotermal Sahasındaki akışkan kullanıldı. Bunun için, jeotermal santralinde bulunan reaktörde kurulan mini pilot sistemde, laboratuvar koşullarındaki parametrelerin esas alındığı adsorpsiyon deneyleri gerçekleştirildi. Deney sonrasında malzemenin karakterizasyon analizleri, mangan dioksitin rubidyumu adsorpladığını doğruladı. Malzeme içerisindeki rubidyum, kümülatif desorpsiyon işlemi sonucunda 0.32 kat artmış olarak çözeltiye geçti. δ-MnO2, sahada düşük miktardaki (11 ppm) elementler için bile etkili olduğundan rubidyumun jeotermal tuzlu sulardan ayrılması için umut verici bir sorbent olarak bulundu.Master Thesis Enhancement of Ultraviolet Resistance of Polyaspartics(01. Izmir Institute of Technology, 2024) Karabacak, Bahar Demirtaş; Demir, Mustafa MuammerThe degradation of polyaspartic ester (PAE) resins under ultraviolet (UV) exposure poses significant challenges for their long-term use in outdoor applications. This study investigates the enhancement of UV resistance of PAE resins through the incorporation of metal oxide particles as UV absorbers. The research aims to determine the efficacy of metal oxide particles in improving the UV protective properties of PAE resins. Experimental results demonstrate that the UV absorption values of resin dispersions containing metal oxide particles significantly increased compared to pure PAE resin. This enhancement may be attributed to the metal oxides' ability to absorb and scatter UV light, thereby reducing the transmission of harmful UV rays through the resin matrix. Various concentrations of metal oxide particles were tested, and the findings underscore the importance of achieving a homogeneous dispersion within the resin for optimal UV protection. The study concludes that the incorporation of metal oxide particles into PAE resins can remarkably enhance the UV resistance of PAE. The improved UV absorption characteristics make these modified resins more suitable for applications exposed to prolonged UV radiation. This research provides a foundation for further exploration into optimizing particle concentrations and dispersion techniques to maximize the UV resistance of polyaspartic ester resins while maintaining their transparency over visible region of the optical spectrum.Master Thesis Fabrication and Characterization of Perylene Diimide Doped Polyfluorene Based Solution Processed Blue Organic Light Emitting Diodes(2023) Varlıklı, Canan; Utlu, Sevde Nur; Demir, Mustafa Muammer; Varlıklı, Canan; Demir, Mustafa MuammerBlue is considered as the major component in many applications of organic light emitting diodes (OLEDs). Most of the polymeric blue emitters including poli[9,9-di-(2-diethylhexyl)-fluorenyl-2,7-diyl] (ADS231BE) attract attention with their solubility and potential in reducing the application costs, but also suffer from wide electroluminescence resulting in color purity issues. Annealing temperature and solvent choice have great influence on morphology and electronic properties. A typical OLED is fabricated by using ADS231BE as the emitter material and effect of annealing temperature on EL properties is investigated between 60C and 150C. OLEDs produced using toluene have shown better efficiency compared to those using chlorobenzene. Regardless of the solvent used, the efficiencies gradually decreased, but the stability and color purity of the devices increased with increasing annealing temperatures. Surface morphologies were examined, and suitable coating conditions were determined. Small molecule orange-red-emitting N,N'-bis(2-ethylhexyl)perylene-3,4,9,10-dicarboxylic diimide (PDI) derivatives were introduced into the blue-emitting conjugated polymer ADS231BE at a concentration of 0.1 wt.%. Electroluminescence, morphology, photoluminescence and Raman analysis of the developed devices were completed to determine the type of aggregation and conformational change caused by PDI doping. Subsequently, to balance charge and improve the electroluminescent character of the devices, a hole transfer layer (HTL) consisting of Poly (N-vinyl carbazole) (PVK) and PVK:1,3-Bis(N-carbazolyl) benzene (mCP) was added to the device structure. Similar morphological and Raman analyses were performed. Compared to the bare ADS231BE containing devices, without changing the CIE coordinate values, approximately, 10 folds of luminance and more than 5 folds of EQE increments were obtained.Master Thesis Recovery of Lithium From Aqueous System Using Manganese Oxide Adsorbent With Developed Electrospun Mat Substrate(01. Izmir Institute of Technology, 2023) Akgün, Berk; Ebil, Özgenç; Demir, Mustafa MuammerLithium is used in many fields due to its high energy density and unique electrochemical properties. Recently, there has been a strong increase in demand for lithium, so the extraction of lithium from natural water resources has become a remarkable research topic. One of the most effective methods of separating lithium from natural water sources is adsorption using lithium ion-sieve adsorbents. However, the powdered nature of the adsorbents makes them challenging to process and less recyclable. Recent studies have focused on developing adsorbents using different polymeric materials as substrates or binders. In the thesis, as a new approach, flexible and free-standing polyurethane electrospun mat substrates were produced and combined with λ-MnO2 to extract lithium from aqueous systems, and their lithium removal performance was investigated. After the fabricated mats and λ-MnO2 powder were characterized, the deposition process was performed, and filtration studies were carried out in synthetic lithium solution. Optimum conditions for lithium removal were found as an adsorbent amount of 200 mg, and 200 ppm initial [Li+], and pH 12. In addition, lithium removal performances have been improved by stacking mats and multi-stage filtration processes. Lithium removal reached 76.6% when a 400 ppm lithium solution and an 8-step filtration were used. Lithium removal experiments were performed with salt-lake brine containing high concentrations of various ions and showed that these ions reduced the lithium removal. In the study, PU electrospun mats for λ-MnO2 powder were found to be a promising substrate for lithium removal from aqueous systems.Master Thesis Kinetics of Silica Polymerization at Various Conditions(01. Izmir Institute of Technology, 2022) Hasköylü Toker, Öykü Çağ; Demir, Mustafa Muammer; Baba, AlperSilica is the most abundant element on Earth because the Earth's crust is composed mainly of metal silicates. The source of this silica is mainly volcanic rocks, which come to the surface through tectonic activity and are the primary source of heat for geothermal activity. The silica concentration in a geothermal fluid is higher than the solubility limit of natural waters, so scaling of (metal) silicates is often observed in geothermal operations. This situation has become critical for geothermal power plants. Since silicates have an insulating structure, they lead to a reduction in energy efficiency during fluid transport. The formation of silica-rich deposits should be understood to minimize the negative effects of the scaling. Briefly, silicic acid molecules in the reservoir system are condensed, and the monomeric silicic acid molecules bind to each other via covalent bonds. In the course of this reaction, dimers, tetramers and short oligomers are formed, and eventually a large polymeric silica network is formed. In the presence of metals, both the kinetics of polymerization and the structure of the network are inevitably affected. In this study, the presence of kinetic parameters (different salts such as FeCl3, MgCl2, AlCl3 and NaCl), the reaction process, the rate and the activation energy of silica polymerization at different temperatures between 25 and 90 °C were investigated. The yellow silicomolybdate method was used to determine the concentration of monomeric silica. The order of the polymerization reaction was given as 3. The polymerization occurs in the initial phase, in the first 40 minutes, where the activation energy was about 29.52 ± 2.28 kJ/mol and the rate constant was of the order of 4x10-8 mol-2∙L2∙s-1. The results also confirmed that pH has a stronger effect on the kinetics of silica polymerization than temperature. The neutral solution decreases rapidly, while the acidic solution has an induction phase in the first hour of polymerization. Different temperatures did not affect the polymerization rate as much as pH. At 25°C the experiment showed the fastest polymerization, but at 90°C the low concentration changed from the beginning. During all these experiments, no scaling of amorphous silica was observed, only the polymerization of silica.Master Thesis Lithium Extraction From Geothermal Brine by Adsorption Method With Electrolytic Y-Mno2 Sorbent(Izmir Institute of Technology, 2022) Toprak, Seyra; Demir, Mustafa Muammer; Baba, AlperIn recent years, studies on the recovery of lithium metal have attracted great attention due to its wide application areas, especially in lithium-ion batteries. Recovery of lithium from brines is preferred considering the environmental impacts in mining. The application of manganese oxide sorbents to recover lithium from geothermal brines has been extensively studied as it is a potential source of lithium. In this thesis, adsorption was performed in Tuzla Geothermal Power Plant (TGPP) at 87 °C and 2 bar using a mini-pilot system in the reactor near the reinjection well of the plant to investigate the adsorption performance in field conditions. As a new approach, electrolytic manganese dioxide (γ-MnO2), which is widely used as cathode material in batteries, was used as the sorbent material for lithium and its adsorption/desorption performance was investigated. Batch adsorption experiments were performed in synthetic lithium solution and the optimum working conditions were determined as pH 12, adsorbent concentration of 3 g/L, and initial lithium-ion concentration of 200 mg/L. The highest adsorption capacity of the sorbent in the Langmuir model was found as 9.74 mg/g. The maximum adsorption performance was obtained at 1h adsorption in Tuzla GPP. In the continuation of the study, desorption was carried out in acidic medium with the brine-treated sorbent. Lithium concentration was enriched to around 250 ppm with repetitive desorption studies. Reusability of the sorbent was investigated and the reused sorbent showed almost 40% performance compared to virgin powder. γ-MnO2 was found as a promising sorbent for the separation of lithium from geothermal brines.Master Thesis Preparation and Characterization of Serum Albumin Nanoparticles Obtained From Modified Bovine Serum Albumin(01. Izmir Institute of Technology, 2021) Özmen Egesoy, Tuğçe; Akdoğan, Yaşar; Demir, Mustafa MuammerThe serum albumin has been used as a drug nanocarrier for a long time due to its rich drug transportation ability. Here, modified bovine serum albumin (BSA) proteins were obtained by conjugation with ethylenediamine and dopamine molecules, separately. Using these modified proteins, new BSA nanoparticles were obtained by a desolvation method. Native BSA has a net negative charge at the physiological condition. However, ethylenediamine conjugation yields a positive charge on it, and thus produces cationic BSA (cBSA) protein. On the other hand, dopamine functionalization (D-BSA) makes BSA eager to coordinate with transition metals. After preparation of modified proteins (cBSA and D-BSA), their nanoparticles were prepared with desolvation method but using different crosslinking mechanisms. For cBSA NPs preparation, a traditional crosslinking agent of glutaraldehyde was used. However, for D-BSA NPs preparation, Fe(III) ions were added to the system to achieve the stable nanoparticle formation. In order to obtain cBSA NPs, several organic solvents were used as desolvating agents. cBSA NPs with an average size around 200 nm were obtained in a high formation yield (54.8%) only through addition of acetonitrile to the cBSA aqueous solution. Similarly, different desolvating agents were studied to obtain D-BSA NPs. The promising results were obtained upon addition of 1:5 (v/v) of water/acetone mixture. After addition of the desolvating agent, Fe(III) ions were added to the solution to interconnect D-BSA with each other. This connection is pH sensitive therefore albumin nanoparticles were stable at basic pH values but not at acidic pH values. By this way, pH sensitive D-BSA NPs around 300 nm particle sizes were obtained.Master Thesis Development of a New Antiscalant for Minimization of Stibnite Scaling in Geothermal Binary Plants(01. Izmir Institute of Technology, 2021) Karaburun, Emre Mustafa; Baba, Alper; Demir, Mustafa Muammer; Demir, Mustafa Muammer; Baba, AlperDemand for renewable and sustainable energy resources has been increasing in recent years due to the adverse effects of fossil energy resources (gases, oil, coal ect,) on human health and nature. Since geology properties of our country is rich in geothermal energy resources, there is a remarkable increase in plant capacities every year. Geothermal energy is the energy obtained from the fluid, gas, and steam that have been stored in reservoirs by carrying the heat energy accumulated in the rocks in the depths of the earth or surfaced along the discontinuity zones.The increase in the use of geothermal energy and the increase in the capacity of the power plants has also revealed the problem of scaling. The main cause of deposition are the decrease in solubility of minerals by a decrease in pressure and temperature upon pumping the geothermal brine up to the ground. Calcium carbonate, calcium sulphate, metal silicates (Mg, Fe) are the most widely accepted types of scaling. In recent years, antimony and arsenic sulfide scaling have been encountered in volcanic and metamorphic regions. Between these two types of scaling, antimony sulfide is mostly seen in the heat-exchangers and preheaters where the temperature drops suddenly. In this thesis, the antimony sulfide scaling formed in the geothermal power plant was synthesized in an autoclave reactor under specified conditions. Water-soluble polymers nominee for being antiscalants such as Poly (vinyl sulfonic acid), Poly (acrylamide-co-vinyl sulfonic acid), Poly (acrylamide-co-vinyl phosphonic acid), Alginic Acid, Natural antiscalants, Polyacrylic acid, and Polyvinyl alcohol were employed. The results suggest that polymers containing vinyl sulfonic acid and acrylamide likely shows remarkable progress in increasing the concentration of ions in decantate, particularly at low dosages. (≈5 ppm)Master Thesis Fabrication and Characterization of Ceramic Fibers From Preceramic Polymers(Izmir Institute of Technology, 2019) Özmen, Ecem; Ahmetoğlu, Çekdar Vakıf; Demir, Mustafa MuammerCeramic fibers which are classified as oxide and non-oxide fibers are preferred to use in applications which are carried out at high temperature since they have high strength, low thermal expansion, corrosion, and oxidation resistance. Non-oxide fibers are generally produced using preceramic polymers by the spinning method. The production of ceramic materials using preceramic polymers by spinning method is more advantageous than other methods since the production of complex materials could be achieved at lower temperatures. The preceramic polymer family is basically classified as polysiloxane, polysilazane and polycarbosilane. In this thesis, it was aimed to obtain ceramic fiber in the most economical way. In this context, a spinning device was designed and made. Additionally, polysiloxane which is the most economical preceramic polymer was used to produce ceramic fiber. Polysiloxanes were spun by melt spinning. Obtained fibers were cured by different methods. As a result of pyrolysis, 65-130 μm thickness SiOC fibers were achieved.
- «
- 1 (current)
- 2
- 3
- »