Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
3 results
Search Results
Master Thesis Piezocatalytic and Piezoelectric Properties of P(vdf) and Its Copolymer/Terpolymer Films(01. Izmir Institute of Technology, 2023) Tengizdeniz, Ceren; Adem, Umut; Genç, AzizNowadays, the release of colored organic pollutants such as Rhodamin B dye, resulting from industrial activities endanger the people, animals, and plants. Many methods have developed to destroy these harmful pollutants. Piezocatalysis, a newly used environmentally friendly method, takes advantage of the piezoelectric effect, and uses mechanical vibration to produce active species on opposite surfaces of matter for degradation of dye. In this study, piezocatalytic and piezoelectric properties of P(VDF) based homopolymer, copolymer and terpolymers were investigated. With the addition of 2nd and 3rd monomer to the homopolymer, observation of change in piezoelectric and piezocatalytic properties and removal efficiency of pollution in water, were aimed. P(VDF) homopolymer, P(VDF-TrFE) copolymers with composition of 55/45 and 50/50 mol%, and P(VDF-TrFE-CTFE) terpolymer with 62/31/7 mol% were synthesized by solution casting method. It was observed that the 2nd and 3rd monomer added to the homopolymer enhanced the piezoelectric properties and strain characteristics of the polymers. Maximum polarization and strain of terpolymer was observed as 11 µC/cm2 and 5.6 %, respectively. Due to the increase in piezoelectricity, a noticeable increase in piezocatalytic properties was observed. Terpolymer exhibited the highest and most efficient piezoelectric and piezocatalytic performance. P(VDF) homopolymer was reached 27% dye degradation efficiency. While copolymers with mol% 55/45 and 50/50, dye degradation efficiencies were 40% and 47%, respectively, terpolymer efficiency was 54%. From the dielectric measurements, within the transition region (49 mol% ≤ CVDF ≤ 55 mol%) of P(VDF-TrFE), both normal-ferroelectric and relaxor characteristics were observed. Terpolymer showed relaxor properties as expected.Master Thesis Characteristic Properties and Recyclability of Aluminium Beverage Cans and Coffee Capsules(Izmir Institute of Technology, 2022) Önen, Rabia; Genç, Aziz; Gökelma, MertolRecycling is an effective way to reduce environmental pollution. Recycled aluminium uses 95% less energy than primary production. Therefore, there is a high demand for more efficient recovery technologies. Aluminium is used in transportation, consumer products, and electronics. Short life cycles, thin walls, and surface coatings make aluminium recycling difficult. This study focuses on UBCs and coffee capsules' properties and recyclability (CCs). A lab-scale electrical resistance heating chamber furnace was used for the de-coating and remelting experiments. The coatings were characterized using Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS). As a result of the study, it was found that thermal pre-treatment temperature is more critical for alloys that have high Mg content due to their oxidation tendency. Suitable thermal pre-treatment temperature was observed between 520 to 550 °C for the samples. On the other hand, when the volatile organic content of the scraps was analyzed, it was observed that clean UBCs and CCs contain 2.2% and 9% volatile organic content, respectively, but it can be increased with increasing drink rest inside of it. A result of these experiments shows that the metal yield can differ up to 3.5% due to the drink residues (sugar). Also, it was observed that high-density pressing of the samples prior to the de-coating process increases the amount of the entrapped carbonaceous materials and decreases the de-coating efficiency. Finally, it was observed that samples with low wall thicknesses should be remelted under a salt flux to prevent oxidation and allow coalescence.Master Thesis Synthesis of Titanium-Based Powders From Machining Waste by Using the Hydrogenation-Dehydrogenation Method(Izmir Institute of Technology, 2022) Çuhadaroğlu, Zeynep; Genç, Aziz; Gökelma, Mertol; Genç, Aziz; Gökelma, MertolSustainability and recycling activities have gained importance in almost every field all over the world. Many studies are conducted to recycle titanium and titanium alloys owing to their outstanding properties like low density, biocompatibility, corrosion resistance, and high strength-to-weight ratio. Although they offer superior properties, their usage is limited due to their high production cost and potential to generate waste, and therefore, recycling activities in this area should be expanded using an appropriate method. Cold hearth melting, vacuum arc re-melting, and hydrogenation and dehydrogenation process are widely used for recycling titanium scraps in industry. Among them, the hydrogenation and dehydrogenation (HDH) process has a significant environmental and economic impact. In this thesis, titanium powders were synthesized from additive manufacturing turnings. Ti-6Al-2Sn-4Zr-6Mo turnings were used as starting materials on which HDH characteristics were not investigated in the literature. Both hydrogenation and dehydrogenation parameters were studied to reach optimum conditions. Our results revealed that hydrogenation was accomplished at 500 °C for 120 minutes with 5 °C/minute heating rate. The optimum dehydrogenation condition was found at 600 °C for 90 minutes. Ti-6Al-2Sn-4Zr-6Mo powder with average 56 μm particle size was synthesized; however, hydrogen and oxygen concentrations in the powder were not at the desired level and non-spherical shaped powders were produced end of the process.