Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Investigation of Different Uv Stabilizer Effects on Hdpe Grades(Izmir Institute of Technology, 2019) Germen, Oktay; Şeker, ErolIn this study, a performance Hindered Amin Light Stabilizer (HALS), used to prevent the structure of polymeric materials from UV and thermal degradation, was investigated using High Density Polyethylene (HDPE) injection grade. The primary goal of this study is to understand the effects of different HALS types, that consist of low molecular mass and high molecular mass, on mechanical and physical properties of HDPE using a design of experiment method. In addition, Minitab program was used to analyze the data, obtained with the experimental design, with ANOVA analyses to estimate the OIT and Loss Elongation% responses of the samples made with varying HALS amounts and types. Briefly, Elongation Lost% which is the ratio of Elongation% Before Aging to Elongation % After Aging and OIT(Oxidative Induction Time) were studied in different recipes of HDPE Injection Molding Plaque specimens in order to measure the effect of HALS1 (Tin770), HALS2(Tin622) and HALS3(Chim944) on aging. One-year of aging was simulated using a standard aging chamber. It was observed that synergetic effect of HALS1 with HALS3 was much more effective than thatof HALS2 with HALS3. Moreover, it was determined that the samples containing antioxidant which did not contain any HALS additive were completely degraded at the end of the same aging process. This study showed that OIT results of samples were affected directly by the amount of HALS3 which protected the polymer against long-term exposure to UV radiation and high temperature whereas neither HALS1 nor HALS2 showed the same protection.Master Thesis Growth and Characterization of Znsno Thin Films on Polymers for Oleds(Izmir Institute of Technology, 2019) Ekmekçioğlu, Merve; Aygün Özyüzer, GülnurThe use of flexible organic light-emitting diodes (OLEDs) in smartphones and televisions with inclined screen shows significant improvements in commercial applications. Recently, flexible OLEDs have been used in lightweight, portable, wearable and even deformable screens, sensors as well as solid-state lighting applications. Under favour of these applications, remarkable developments are observed in the production of flexible electronics. The advantages of OLEDs according to the existing liquid crystal display (LCD) technology are self-emission capability, wide viewing angle, fast response time, simple structure, and low driving voltage. Highly conductive and transparent anodes are required for efficiency and uniform light emission in OLEDs. Indium tin oxide (ITO) which is one of the most promising anodes among transparent conductive oxides (TCO), has superior electrical and optical properties such as ~85% high transmittance at the visible region and ~104 Ω−1 cm−1good conductivity. The reason is due to the bandgap range of about 3.70 eV. Zinc tin oxide (ZnSnO or ZTO) is another TCO commonly used for many applications in the literature. Alternative anodes eliminate the use of ITO due to the absence of indium element so that highly desirable. In this thesis, ZTO is used as anode instead of ITO thin film and the eligibility of ZTO as an anode in OLED production is explored. The advantages of the optimized ZTO thin film according to the ITO are that is abundant on earth, has better performance, has low surface resistance, has less surface roughness, is capable of being produced as an anode in OLEDs. In this thesis to be successful, at the first stage ZTO thin films have grown on soda lime glass by magnetron sputtering, then ZTO and ZTO/Ag/ZTO multilayer thin films respectively have been deposited on flexible Polyethylene terephthalate (PET) and Polyimide (PI) substrates by magnetron sputtering method. In this way, the best coated thin films have been investigated using spectrophotometry, energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), Xray diffraction (XRD) and Raman spectroscopy.Master Thesis Sericin-Polymer Conjugates: Preparation and Physicochemical Characterization(Izmir Institute of Technology, 2017) Gül, Abdulkadir; Bulmuş Zareie, Esma VolgaSericin is a protein derived from silkworm, Bombyx mori, and has several useful properties as a natural biomaterial such as antioxidant character, moisturizing ability, hydrogel forming property and most importantly immunogenic inertness. The aim of this thesis is to prepare and physicochemically characterize sericin-polymer conjugates as potential natural-synthetic hybrid biomaterials with enhanced properties for drug delivery and tissue engineering applications. For this purpose, three polymers having the same degree of polymerization (n~42) and varying chemical nature, i.e. poly(oligoethylene glycol methacrylate), P(OEGMA) hydrophilic and neutral, poly(hydroxyethylmethacrylate) P(HEMA) less hydrophilic and neutral, and poly(dimethylaminoethyl methacrylate) P(DMAEMA) hydrophilic and cationic after quaternization, were first synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. Each polymer was characterized via nuclear magnetic resonance (1H-NMR) and gel permeation chromatography (GPC). Separately, molecular weight and isoelectric point of sericin were characterized using various techniques including Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) and High-Resolution Two-Dimensional Polyacrylamide Gel Electrophoresis (2D-PAGE). Polymers were then covalently conjugated to sericin using NHS/EDC chemistry. The conjugates were characterized using SDS-PAGE, GPC and DLS (Dynamic Light Scattering). The SDS-PAGE and GPC results showed the successful preparation of the conjugates. DLS revealed that the hydrodynamic size of P(OEGMA) and P(DMAEMA) polymers and their conjugates were between 1 and 10 nm as they are soluble in PBS and do not form aggregates. Unlike the other two polymers, although the size of P(HEMA) polymer was observed to be 3.24 ± 0.62 nm, the DLS measurements of P(HEMA) conjugates indicated the presence of self-organization and aggregation of Sericin-P(HEMA) conjugates in aqeuous solution. Consequently, the size of sericin-P(HEMA) conjugates were found to be 530 ± 60.83 and 223.3 ± 25.2, respectively.Master Thesis Integration of Red & Blue Tl Materials To Different Polymer End-Use(Izmir Institute of Technology, 2016) İncel, Anıl; Demir, Mustafa MuammerTriboluminescence (TL) is known as the emission of light upon the application of any mechanical force. In this master thesis, two organometallic-based TL crystals, which are EuD4TEA and Cu(NCS)(py)2(PPh3) were obtained and they were integrated in the transparent polymers: poly (methylmetacrylate) (PMMA), poly (styrene) (PS), poly (urethane) (PU) and polyvinylidene fluoride (PVDF) for different end-use. In the development of composites, two different processes were carried out: i) embedding (or blending) and ii) surface impregnation. The different end-use polymers were used as transparent polymer film, electrospun nanofibers, and nanobeads. TL performance of composites were investigated by using drop tower system which was specficically designed for this research. Atomic force microscopy (AFM), scanning electron microscopy (SEM) were used to characterize the topographic and morphologic properties of both polymers and composites. Additionally, fluorescence microscopy helped to understand the signal of emitted light by composites. Lastly, piezoelectric properties of composite materials were invetigated by oscilloscope. According to results, type of process, particle size of crystal, surface property and form of host material (polymer), the concentration of crystalline particles in composites were determined as the main parameters and the results were estimated with respect to these parameters. PU-based composite film and fiber show better stability towards mechnical stress rather than PMMA, PS, and PVDF due to the roughness surface of thin-film surface for film-based composites, smallest wickerwork formation of electrospun mats for fiber-based composite, and the chemical affinity of PU with TL crystals.Master Thesis Development of Antibacterial Polymer Based Nanocomposite Materials(Izmir Institute of Technology, 2015) Abatay, Ezgi; Arslanoğlu, Alper; Tanoğlu, MetinHuman beings are often infected by microorganisms such as bacterium, mold, yeast, virus, etc. in the living environment. It became a requirement and a necessity to create sterile fields in areas. Composite stones are one of the main materials that can be used for the contact surfaces in indoor and outdoor places due to their being of highly resistant to abrasives, chemicals and impacts. Research has been intensive in antibacterial material containing various inorganic substances. The aim of this thesis is investigating the antibacterial effect of inorganic substances such as silver, zinc oxide, calcium oxide, titanium oxide and magnesium oxide on stone products. This study also deals with the silver doped zinc oxide powder and their antibacterial efficacies. Stone product is formed of mainly two type compound which are quartz aggregates as reinforced and filler and thermoset polyester resin as matrix. The manufacturing process begins with selection of raw quartz materials. They are crushed and blended in the ratio of 90 % quartz aggregates to 10% polyester matrix and other additives such as antibacterial agent, pigment. These united constituents are used for production of composite stones by applying those combined vacuum, vibration and pressing processes which are named as vibropress, simultaneously. Following it, they are subjected to surface preparation and polishing processes. In this study, mechanical, thermal, and morphological properties of the particles, polyester matrix and stone product were investigated. Antibacterial efficacies of these were investigated based on colony-count method against gram negative (E.coli) and gram positive (Bacillus subtilis) bacteria. Silver-containing stone samples showed best antibacterial property about ninety-nine percent reduction.Master Thesis Development of Arginine-Containing Well-Defined Polymers(Izmir Institute of Technology, 2014) Taykoz, Damla; Bulmuş Zareie, Esma VolgaThe aim of this work is to synthesize arginine-containing well-defined polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization and perform preliminary investigation on the use of these polymers in nucleic acid complexation for potential gene therapy applications. Pentafluorophenyl methacrylate (PFMA) was chosen as an active ester monomer to produce polymers having functional groups available for further modification. RAFT polymerization of PFMA was performed varying polymerization conditions such as feed composition and polymerization temperature. Polymers (PPFMA) were characterized using nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography. Linear increase in ln[M]0/[M] with polymerization time, and number average molecular weight (Mn) with monomer conversion indicated RAFT controlled polymerization of PFMA under the conditions tested. Furthermore, block copolymers of PFMA with poly(ethylene glycol) methacrylate (PEGMA) as a biocompatible component were prepared. Copolymerization was studied using both P(PFMA) and P(PEGMA) as macro RAFT agent. Copolymerization kinetic studies indicated that chain extension block copolymerizations were successfully performed using both macroRAFT agents. P(PFMA) was reacted with arginine methylester (AME) in the presence of triethylamine (TEA). 100% of P(PFMA) active ester groups could be modified with AME at a polymer/AME/TEA mole ratio of 1/1/3, as determined by 1H-NMR spectroscopy. The AME modified polymers were complexed with a 681-bp DNA fragment through electrostatic interactions at varying nitrogen/phosphate (N/P) ratios. Gel electrophoresis experiments revealed that AME-modified P(PFMA) was able to complex with DNA at a N/P ratio of 200. Furthermore, the hydrodynamic diameter (Dh) of polymer/DNA complexes in phosphate buffer saline was found to be 58 nm, while the free DNA displayed a Dh of 109 nm, indicating the complexation of DNA by AME-modified P(PFMA).Master Thesis Selective Loading of Organofilic Ag Nanoparticles in Ps-Pmma Blends(Izmir Institute of Technology, 2014) Tüzüner, Şeyda; Demir, Mustafa Muammer; Ebil, ÖzgençThe association of nanoparticles with polymer blends offers significant features beyond the advantages of polymer composites prepared by single homopolymer. Since the blends undergo phase separation due to incompatibility of the constituent polymers into various internal structures, the particles can be segregated into one of the phases. Different location of the particles allows to develop novel microstructures; and thus, control over physical properties. In this study, Ag nanoparticles were prepared by reduction of AgNO3 via NaBH4. The particles were capped by cetyl ammonium bromide (CTAB) and were mixed with equimass blend of polystyrene (PS) and poly(methyl methacrylate) (PMMA) in tetrahydrofurane (THF). The solid content of blend solution was fixed at 2.5% w/v. The concentration of the particles with respect to polymer blend was at 0.7 wt %. The composite film was cast on glass slide. Surface feature of the composite films was examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The surface of blend film without particles shows spherical pits with a size of 4.5 μm and rich in terms of PMMA. When particle size was small (diameter is around 20 nm), they preferentially located at the interface of the domains. The large particles with a diameter of 90 nm were found to locate in PMMA phase. Upon annealing of the composite film at 165 ˚C for 3 days, the particles move to the PS domains independent of the particle size and merely PS loaded composite is achieved.Master Thesis Numerical Study of Enhancement of Plastic Rotation Capacity of Seismic Steel Moment Connections by Fiber Reinforced Polymer Materials(Izmir Institute of Technology, 2008) Alkan, Deniz; Eğilmez, Oğuz ÖzgürFlange and web local buckling in beam plastic hinge regions of welded Steel Moment Frames (SMF) can prevent the beam-column connections to achieve adequate plastic rotations under earthquake induced forces. Reducing the web-flange slenderness ratios is the most effective way in preventing local member buckling as stipulated in the latest earthquake specifications. However, older steel beam-column connections that lack the adequate slenderness ratios stipulated for new SMFs are vulnerable to local plastic buckling. This study investigates postponing the formation of local buckles in beam flanges and webs at the plastic hinge region of modified SMF connections (welded haunch) by the use of externally bonded Glass Fiber Reinforced Polymers (GFRP). The research includes finite element (FE) modeling. The energy dissipation capacity of existing SMF connections is anticipated to increase with GFRP laminates bonded to flanges of beams in plastic hinge locations. Cantilever beams with and without GFRP were analyzed under quasi-static cyclic loading and the effects to the plastic local buckling of the GFRP laminates added to the steel beams were observed.Both geometric and material nonlinearities are considered. The mechanical properties of the GFRP material were obtained through standard ASTM tests and were utilized directly in the FE model. Steel beams with flange slenderness ratios of 8 to 12 and web slenderness ratios of 40-60-80 were analyzed. Results indicate that GFRP strips can effectively delay the formation of local plastic buckling in the plastic hinge region.Master Thesis Preparation and Characterization of Polymer-Zeolite Composite Membranes(01. Izmir Institute of Technology, 1999) Ebil, Özgenç; Çiftçioğlu, MuhsinThis thesis is on the investigation of polymer-zeolite composite membranes for gas separation and the effects of a number of parameters such as solvent and zeolite type, zeolite content, polymer/solvent ratio and preparation temperature on the microstructure of the final membrane. Although there is an increasing interest in polymeric composite membranes, most of the previous work concentrated on the synthesis and performance measurements of new membrane materials rather than the effects of different methods and parameters on processmg.In this study polymer-zeolite composite membranes were prepared by a phase inversion technique. Polysulfone, natural zeolite and synthetic zeolite 13X were used as polymer and second phases respectively. Dichloromethane and dimethylformamide were used as solvents. Four experimental sets of membranes containing the same polymer but different solvents and zeolites with increasing zeolite loadings were prepared and characterized by thermo gravimetric analysis, infrared spectroscopy, optical microscopy and scanning electron microscopy.It has been found that the types of the solvent and zeolite directly affect the final microstructure of the membranes. Solvent removal rate and distribution of zeolite particles are important and have strong effects on the mechanical performance of the membranes.Membranes prepared by using synthetic zeolite 13X and dichloromethane were determined to be the best zeolite distributions in the microstructure by optical microscopy and thermogravimetric analysis. Uniform and mechanically strong membranes with 20-60 % synthetic zeolite contents were prepared. Mechanically weak and relatively nonuniform membranes were prepared by using natural zeolite clinoptilolite. The incorporation of an ultrasonic treatment of the zeolite dispersion most likely contributed in the successful deagglomeration of the second phase in the polymer matrix.Master Thesis Measurement and Modeling of Thermodynamic and Kinetic Data of Membrane Forming Systems(Izmir Institute of Technology, 2007) Arslan, Mine Özge; Alsoy Altınkaya, SacidePhase inversion process involving a ternary system (nonsolvent/solvent/ polymer) isfrequently used to prepare porous and asymmetric polymeric membranes. The thermodynamic and kinetic data for the ternary system are required to understand membrane formation mechanisms, change the preparation conditions and predict the final structure of the membranes. In this study, cloud point curves for polysulfone (PSf)/1-methyl-2-pyrrolidinone (NMP)/water, PSf/tetrahydrofurane (THF)/water, PSf/NMP/ethanol, PSf/THF/ethanol, polymethyl methacrylate (PMMA)/acetone/water, PMMA/ THF/water, PMMA/acetone/formamide and PMMA/THF/formamide systems were measured by titrating polymer solutions with nonsolvents until the onset of turbidity.Binodal curves were calculated by using the Flory Huggins theory with constant interactionparameters. Theoretical ternary phase diagrams were found to be in good agreement with experimental cloud point data. In addition to liquid liquid equilibrium data, sorptionisotherms and diffusion coefficients of water, ethanol and chloroform were measured byusing a magnetic suspension balance. Results of kinetic studies have shown that water sorption in PSf films exhibits Fickian diffusion while anomalous diffusion is observed for ethanol and chloroform sorption. The kinetic data for water sorption was analyzed using a simple Fickian diffusion model to determine the diffusion coefficients. On the other hand, anamalous sorption kinetics were interpreted by a mathematical model involving independent contributions from Fickian diffusion and polymer relaxations. The model successfully fits non-Fickian anomalies including sorption overshoot and allows to determine diffusion coefficients and relaxation times. Diffusivities of penetrants in PSf was found to decrease in the following order: Water > Chloroform > Ethanol. Equilibrium sorption isotherms of ethanol and chloroform are well described by classical Flory Huggins thermodynamic theory with constant interaction parameters. A modified version of this theory for concentration dependent interaction parameter is used to correlate the sorption isotherm of water. Vrentas Duda free volume theory is able to correlate diffusivity data of water collected at 30 C and 40 C while the theory fails to correlate the diffusivities of ethanol and chloroform both of which were determined from diffusion-relaxation model.