Yazar "Akarken, Gürkan" seçeneğine göre listele
Listeleniyor 1 - 8 / 8
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Fabrication and characterization of metakaolin-based fiber reinforced fire resistant geopolymer(Elsevier, 2023) Akarken, Gürkan; Cengiz, UğurGeopolymers have many advantages over Portland cement, such as low energy cost, reduced greenhouse gas emissions, high compressive strength, high-temperature stability, low thermal conductivity, and high strength at an early age. This study obtained fiber-reinforced geopolymer composite (FRGC) structures using metakaolin (MK) basalt and glass fiber, and the fire-resistant FRGC structure was developed. The morphology, structure, and thermal characterization of fire-resistant FRGC were obtained using SEM, TEM, XRD, XRF, FTIR, and TGA. As a result of SEM, FT-IR, and TGA analyses, it was observed that high-temperature geopolymer samples retained their stable structure. The SEM images also indicated the fiber's effect on preventing surface cracking. Fireresistant properties were tested by heat exposure in a muffle furnace for thermal behavior of 200, 400, and 800 degrees C. The mechanical stability of the FRGC blocks was tested using the compression test before and after exposure to high temperatures. In this test, the FRGC block, kept for one hour at 200 degrees C, still has the compressive strength at the high strength concrete class and can be used in skyscrapers (51-76 MPa).Öğe From surface to core: Exploring bulk hydrophobicity in geopolymer tiles(Elsevier Sci Ltd, 2025) Akarken, Gürkan; Cengiz, UğurThis study presents a pioneering approach to produce superhydrophobic bulk geopolymer tiles (SBGT) using a novel concurrent polymerization and cold-press technique. Unlike traditional hydrophobic coatings that degrade over time, this method achieves bulk hydrophobicity by integrating fluoroalkyl silane (FAS) modification directly into the geopolymerization process. The exothermic heat released during geopolymerization was utilized to trigger a sol-gel reaction, enabling chemical grafting of the hydrophobic agent within the geopolymer matrix. The resulting SBGT materials exhibited exceptional hydrophobic properties, with water contact angles (WCA) exceeding 150 degrees, demonstrating complete superhydrophobicity based on both static and dynamic criteria. Selfcleaning tests confirmed the high dust-repelling capability, and liquid resistance tests demonstrated strong non-wettability against common household liquids (coffee, tea, wine, and milk). Furthermore, sandpaper abrasion and water dripping tests revealed that SBGTs maintain their hydrophobicity even under mechanical stress, highlighting their long-term durability. Additionally, mechanical strength analyses showed that while moderate FAS concentrations enhanced flexural strength, excessive amounts led to a decline due to microstructural disruptions. X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDX) analyses confirmed the transformation of the geopolymer into an amorphous aluminosilicate gel, reinforcing its mechanical integrity and water resistance. This is the first study to successfully implement simultaneous concurrent polymerization and hydrophobic modification in cold press geopolymer synthesis, producing a fully hydrophobic bulk material without post-processing treatments. These findings demonstrate the commercial potential of SBGTs for selfcleaning, moisture-resistant, and energy-efficient building applications.Öğe Hydrothermal Synthesis of CuO Nanoparticles: Tailoring Morphology and Particle Size Variations for Enhanced Properties(Çanakkale Onsekiz Mart University, 2024) Akarken, Gürkan; Cengiz, Uğur; Bektaş, Tijen EnnilTransition metal oxides, particularly copper oxides, have garnered significant attention due to their intriguing photochemical, photomagnetic, photo-thermal, and photoconductive properties. Among these, CuO stands out as a p-type semiconductor having narrow bandgap energy ranges from 1.2 to 2 eV, finding versatile applications such as gas sensing, magnetic storage, solar energy conversion, photocatalysis, supercapacitors, field-emission emitters, and optical switches. Additionally, it serves as a crucial component in materials designed for lithium-ion electrodes. In this study, five different CuO nanoparticles were synthesized by simple and cost-effective hydrothermal method with various reaction temperatures and times in a teflon lined stainless steel autoclave. Copper (II) chloride dihydrate was used as copper source in this process. Various characterization techniques were conducted including X-ray powder diffraction (XRD), Raman spectroscopy, and transmitting electron microscopy (TEM). The effect of temperature and time on synthesis process was characterized and discussed. TEM images show that particle size of CuO increase with the temperature and reaction time. First reaction had the smallest particle sizes (mostly around 9-11 nm). This can be attributed to its lowest reaction temperature and shortest reaction time. For the other reactions, two of them accumulate around 19-35 nm and two around 27-45 nm range. However, the rise in the particle’s diameters is not directly proportional to temperature and time. As a result, CuO nanoparticles have been produced with simple method for the market. It can be produced in large quantities for heat exchangers, gas sensing, magnetic storage, solar energy conversion, photocatalysts, supercapacitors, etc.Öğe Innovative Geopolymer Tiles for Indoor Humidity Control: A Comparative Study of Moisture Buffering Performance(Amer Chemical Soc, 2025) Akarken, Gürkan; Yıldırım, Yıldız; Cengiz, UğurGeopolymers have attracted increasing attention due to their unique properties in the construction industry. In this work, innovative geopolymer tiles were evaluated regarding their potential to control indoor relative humidity as a passive construction material. Our production process systematically develops geopolymer tiles with elevated moisture buffering capabilities using four distinct metakaolins and one commercial metakaolin to make a comparison. A critical metric for evaluating hygroscopic materials' capacity to control the indoor humidity change is the moisture buffer value (MBV). The geopolymer tiles' MBV was determined by the Nordtest method in a controlled climate chamber. Additionally, a custom-designed moisture buffer test and strength measurements were conducted, including inspections of the physical appearance after the tiles were submerged in water for 7 days. The results indicate that the geopolymer tiles exhibit exceptional moisture buffering performance, with MBV values ranging between 5.68 and 7.94 (g/m2 Delta%HR). These are the highest and one of the first values for geopolymer tile moisture buffer values in the literature so far. The text discusses the advantages and superior performance of these tiles compared with conventional methods, supported by mechanical, morphological, and structural analyses.Öğe Kendi kendini temizleyen ve ısı yalıtım özelliği olan jeopolimer karo üretimi(Çanakkale Onsekiz Mart Üniversitesi, 2025) Akarken, Gürkan; Cengiz, UğurDünya genelinde hızla artan kentleşme, inşaat sektöründe çevre dostu ve sürdürülebilir yapı malzemelerinin geliştirilmesini zorunlu hale getirmiştir. Geleneksel Portland çimento (PÇ) bazlı beton üretimi, yüksek karbon salınımı ve yoğun enerji tüketimi nedeniyle çevresel sürdürülebilirliği tehdit etmektedir. Bu nedenle, düşük karbon ayak izine sahip alternatif bağlayıcı malzemeler büyük önem kazanmıştır. Bu tezde, metakaolin (MK) bazlı jeopolimer karoların oda sıcaklığında soğuk presleme yöntemiyle üretilmesi ve bu karolara ısı yalıtımı ile kendi kendini temizleme özelliklerinin kazandırılması amaçlanmıştır. Çalışmada, farklı presleme basınçları, sıvı/katı oranları ve dört farklı silan bazlı hidrofobik ajan (%1,25, %2,50, %3,75) kullanılarak jeopolimer karolar sentezlenmiştir. Üretilen numuneler mekanik dayanım, FTIR, XRD, SEM, su temas açısı, kendi kendini temizleme, aşınma, termal iletkenlik ve TGA analizleriyle karakterize edilmiştir. Sonuçlar, %2,50 OTES katkılı ve %30 alkali oranına sahip karoların 20,23 MPa eğilme dayanımı sergilediğini; %3,75 FAS katkılı numunelerin ise 161° temas açısı ile üstün su itici özellik gösterdiğini ortaya koymuştur. Yapılan analizler, hidrofobik ajanların jeopolimer matrise başarıyla entegre olduğunu ve kompakt bir yapı oluşturduğunu doğrulamaktadır. Bu çalışma, jeopolimer karoların sürdürülebilir, enerji verimli ve uzun ömürlü yapı malzemeleri olarak geleneksel seramik karolara alternatif oluşturabileceğini göstermektedir.Öğe Production and characterization of heat retardant fiber-reinforced geopolymer plates(Kare Publishing, 2022) Gezer, Türkan; Akarken, Gürkan; Cengiz, UğurThis paper presents an alternative environment-friendly thermal insulation material for the construction industry. This study aimed to produce this building material with superior heat resistance properties and comparable strength to the concrete produced with Ordinary Portland Cement. The primary purpose of the experimental studies was to produce a basic geo-polymeric plate and to add cellubor and polypropylene fibers to the geopolymeric mortar. In the next stage, fiber-reinforced plates were prepared, thermal experiments were carried out, and discussions and conclusions were formed according to the results and findings. This study initially produced different types of fiber-based metakaolin plates with high heat re-sistance. Then, the flame test examined the heat resistance of the composite plates formed by the mixture of fibers consisting of cellubor, polypropylene, and cellubor + polypropylene fiber mixtures into geopolymeric mortars. It was found that the metakaolin plates containing approximately 6% by weight of Cellubor in the structure, besides their serious resistance to flame, their heat retardancy properties gave 72% better results than Kalekim (cementitious ceramic tile adhesive) plates and 55% better results than non-fiber metakaolin plates. © 2022, Kare Publishing. All rights reserved.Öğe Self-cleaning superhydrophobic polyester resin production for gel coat applications(Elsevier Science Sa, 2025) Akarken, Gürkan; Cengiz, Uğur; Öztürk, Nagihan; Balkaner, CeydaThis research aimed to develop a superhydrophobic unsaturated polyester resin for gel coat applications, hypothesizing that modifying the primary component, polyester resin, to be superhydrophobic would impart the same property to the gel coat. To achieve this, coating solutions were prepared using two different strategies. The first approach involved complementing resin modification with a condensation reaction. The second strategy involved modifying the polyester resin through simultaneous radicalization and condensation polymerization. The superhydrophobic, self-cleaning gel coat applications were applied using a spray coating technique. Subsequently, wettability tests, including contact angle measurements and self-cleaning performance assessments, as well as surface morphology analyses using SEM, AFM, and XPS, were conducted. Additionally, structural characterizations of the composite material were performed using FTIR, XRD, and TGA. The water contact angle of the unmodified polyester resin, initially 84 degrees, increased to 173 degrees, demonstrating the successful production of superhydrophobic polyester resin. It is believed that the produced gel coat will not only result in significant labor savings due to its self-cleaning properties and corrosion protection but will also reduce the use of environmentally harmful cleaning agents.Öğe Yangın geciktirici jeopolimer malzeme üretimi ve karakterizasyonu(Çanakkale Onsekiz Mart Üniversitesi, 2019) Akarken, Gürkan; Cengiz, UğurPortland çimentosu, günümüzde kullanımda olan en üst düzey mühendislik yapı malzemelerinden biridir. Olağanüstü termal performansı, mekanik özellikleri ve dayanıklılığı nedeniyle beton için bağlayıcı bir madde olarak kullanılmaktadır. Bununla birlikte üretimi sırasında muazzam enerji tüketimi ve karbondioksit (CO2) salınımı konusunda çevresel açıdan bir tartışma vardır. Sanayide çimento üretimi, küresel ısınmanın en büyük sebeplerinden biridir. Bu nedenle jeopolimerler, çevre dostu yanmaz yapı malzemeleri; ses, ısı yalıtıcıları, tehlikeli atıkların kapsüllenmesi gibi uygulamalarla dikkat çekmektedir. Jeopolimerler portland çimentosuna göre düşük enerji maliyeti, azaltılmış sera gazı salınımları, yüksek basınç dayanımı, yüksek sıcaklık kararlılığı, düşük ısıl iletkenlik, erken yaşta yüksek dayanım gibi birçok avantaja sahiptir. İnorganik polimer kullanarak yangına karşı koruma, yeni bir mühendislik teknolojisi uygulamasıdır. Jeo-polimer kompozit malzemeler avantajları nedeniyle bu açıdan umut vericidir. Uçucu kül veya yüksek fırın cürufu gibi atık malzemelerden üretilen alkali aktif jeopolimerler, çevresel sürdürülebilirliği ve düşük maliyeti nedeniyle özellikle avantajlıdır. Ancak, devamlılıkları ve işlevsellikleri daha fazla çalışmaya konu olmaya devam ediyor. Jeo-polimer malzemeler, kaynak malzemelerin ve aktivatörlerin kimyasal bileşimine bağlı olarak, ateşe ve ısıya dayanıklı kompozitler gibi çeşitli uygulamalarda kullanılabilir. Bu çalışmada, yangına dayanıklı jeopolimerlerin üretilmesi için farklı reçeteler uygulanmış ve karakterizasyon çalışmaları yapılmıştır. Metakaolen esaslı, bazalt fiber ve kırpılmış cam elyaf katkılı jeopolimer kompozit yapılar elde edilmiştir. Üretilen numunelerin termal özellikleri, mikro yapıları, mukavemetleri, bileşimleri test edilmiştir. Örnekler, doğası ve bileşimlerini incelemek için X-ışını Kırınımı (XRD), termal davranış için termogravimetrik analiz (TGA) ve kül fırınında ısıya maruz bırakma, temel bileşimlerini belirlemek için X-Işını Floresans (XRF) ve ftir spektroskopisi (FTIR) gibi çeşitli karakterizasyon teknikleri ile incelenmiştir.
