Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Effects of Surface Treatments on Fatigue Performance of Adhesively Bonded Single Lap Joint Carbon Fiber Based Polymer Composites(01. Izmir Institute of Technology, 2024) Gürbüz, Ahmet Ayberk; 01. Izmir Institute of TechnologyYeni teknolojilerin ortaya çıkışını takip eden dönemde, alternatif birleştirme teknikleri karbon elyaf takviyeli polimerleri içeren uygulamalarda geleneksel mekanik bağlantı elemanlarının yerini almaya başlamıştır. Gerilme konsantrasyonu, ağırlık, radar sinyallerinin emilmesi ve korozyon gibi mekanik bağlantı elemanlarıyla ilgili zorlukların çoğu, CFRP'ler alanında yapıştırıcı bağların kullanılmaya başlanmasıyla etkili bir şekilde ele alınmıştır. Bununla birlikte, kirletici maddelerin varlığı ve yüzey tabakasındaki matris fazlalığı da dahil olmak üzere çeşitli faktörler yapışma gücü üzerinde önemli bir etkiye sahiptir. Bu tezin amacı, yüzey işleminin uygulanmasının, yapışkan olarak bağlanmış karbon elyaf takviyeli polimer kompozit plakaların yorulma performansı üzerindeki etkilerini incelemektir. [45/-45/45/0/-45/90]s istifleme sırasına sahip karbon fiber takviyeli polimer laminatlar, otoklav tekniği ile tek yönlü prepregler kullanılarak üretilmiştir. Karbon fiber takviyeli polimer laminatların yapışma yüzeyine lazer işlemi ve elektrospinning olmak üzere iki farklı yüzey işlemi uygulanmıştır. Farklı yüzey işlemlerine tabi tutulan kompozitlerin yorulma performansını araştırmak için yük kontrollü çekme-germe yorulma testleri yapılmıştır. Numuneler, statik tek bindirmeli kesme testlerinden belirlenen ortalama maksimum tek bindirmeli kesme yükünün %30 ila %50'si arasında değişen gerilme seviyelerinde döngüsel yüklemeye tabi tutulmuştur. Yüzey işlemlerinin yapışma yüzeyinin yorulma performansı üzerindeki etkileri SEM görüntüleri, sertlik bozulması ve Wöhler eğrileri kullanılarak yorumlanmıştır.Master Thesis Process Parameters and Mechanical Properties of Geopolymer Glass Foam Structures(01. Izmir Institute of Technology, 2020) Polat, Dilan; Güden, Mustafa; Güden, Mustafa; 01. Izmir Institute of Technology; 03.10. Department of Mechanical Engineering; 03. Faculty of EngineeringThe effects of waste-glass powder particle size (23 and 72 μm), solid/liquid ratio (S/L=1, 1.5 and 2) and aluminum foaming agent content (2-20 wt%) on the expansion behavior of geopolymer slurries were investigated experimentally. Geopolymer slurries were prepared using an activation solution of NaOH (8M) and sodium silicate (10% NaOH, 27% SiO2). The expansions and temperatures of the slurries were measured in-situ using a laser distance meter and a thermocouple, respectively. Few geopolymer foams were sintered at 600, 700, 725 and 750 °C. The compression strengths and thermal conductivities of foam samples were also determined. The expansion of slurries continued until the temperature increased to 85-90 °C. At this temperature, the slurry evaporation; hence, increased S/L ratio limited both the hydrogen release rate and geopolymerization reaction. As the content of Al increased, the final foam density decreased, while the coarse powder slurries resulted in lower densities (240-530 kg m-3) than the fine powder slurries (280-530 kg m-3). Three crystal phases, muscovite, sodium aluminum silicate hydrate and thermonitrite, were determined after the geopolymerization. The muscovite formation was noted to be favored at higher S/L ratios. The partial melting of glass particles started after ~700 °C, while sintering above this temperature decreased the final density. The reduced density above 700 °C was ascribed to the release of carbon dioxide by the decomposition of thermonitrite. Both the compressive strength and thermal conductivity of geopolymer and sintered foams increased at increasing densities and were shown to be comparable with those of previously investigated geopolymer and glass foams. The geopolymer foams sintered at 750 °C exhibited the lowest density and the highest compressive strength.Master Thesis Polyropylene - natural zeolite composite films(01. Izmir Institute of Technology, 1999) Özmıhçı, Filiz; Balköse, Devrim; Özmıhçı, Filiz; Balköse, Devrim; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this project, preparation and characterization of polypropylene natural zeolite composites were studied. Three different series of preparation methods were performed, hot press, microscope slide, and extrusion. The composites are ranged between 0-10 wt%, 0-50 wt%, and 0-6 wt% zeolites, for hot press, microscope slide, and extrusion respectively.Polymer matrix composites are materials which contain polymers as matrix materials surrounding very small reinforcing fibers or fillers. Polymeric composites have great potential from a manufacturing standpoint and show advantages. Such as they are inexpensive, derive from natural sources, present lower density than mineral fillers, and increases the mechanical properties of the final product.In this research polypropylene was used as a matrix material and natural zeolite as a filler. Natural zeolite particles were modified with polyethylene glycol to break agglomerates and make a homogenous dispersion of natural zeolite in polypropylene matrix. These composites were characterized by using differential scanning calorimetry, thermal gravimetric analyzer, infrared spectrophotometer, optical microscopy, mechanical testing and by density measurement device. It has been found that, branched shaped air pockets existed in hot pressed and extruded composites. This causes low mechanical strength, and the densities of these films also indicate the presence of voids in the composite.