Yazar "Bedeloğlu, Ayşe" seçeneğine göre listele
Listeleniyor 1 - 20 / 46
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe DIELECTRIC PROPERTIES OF POLYANILINE-FUNCTIONALIZED CARBON NANOTUBE/PDMS NANOCOMPOSITES(Bursa Uludağ Üniversitesi, 2020) Ünsal, Ömer Faruk; Altın, Yasin; Bedeloğlu, AyşeIn recent years, carbon nanotubes (CNTs) have emerged as materials that are often used in the preparation of polymer nanocomposites with conductive or advanced dielectric properties due to their unique properties including high temperature and electrical conductivity, which allows the production of very light and robust materials with a very high length-to-diameter ratio. However, during the preparation of polymeric nanocomposites with these materials, some problems are encountered. One of the major problems is that after preparing these conductivematerials or adding them into the polymer, they tend to aggregate, forming agglomerate, due to their conductive structures. Therefore, in this study, firstly, multi-walled carbon nanotubes (MWCNTs) were functionalized with conductive form of polyaniline (PANI) and subsequently, the poly (dimethyl siloxane) (PDMS) polymer nanocomposite films with different concentrations of functionalized multi-walled carbon nanotubes were prepared. Then, the structural, morphological, electrical and dielectric properties of the films were characterized. As a result, with the addition of only 1.5% PANI-CNT, the dielectric constant of PDMS was increased by 47-fold at 1 Hz. The dielectric films like presented here can be used in capacitors, flexible electronics, dielectric elastomers and artificial muscle applications.Öğe Improving the Water Repellency of Polyester Filament Yarn and Fabrics(Ege Üniversitesi, 2023) Garip, Beysim; Yüksel, Ayten; Ünal, Seda; Bedeloğlu, AyşeWater-repellent finishing is one of the most applied finishing processes by using materials that prevent the wetting of textile products and the passage of water drops. Fluorinated compounds are widely used in conventional methods applied for the development of water repellency, but the threats posed by these to humans and the environment have led to new searches for water repellency. Giving the water-repellent effect by reinforcing the masterbatch during fiber production can provide longer-lasting, homogeneously dispersed and environmentally friendly products. This reason, in this study, filament yarns containing fluorine-free water-repellent additives in three different weight percentages and fabrics coated with a water-repellent finishing without fluorine were produced. Then, the performance properties of the yarns were analyzed and water repellency, tensile and air permeability tests of the fabrics were performed. As coating repetition increased, the water repellency of the fabrics improved and air permeability decreased by approximately 80%.Öğe Investigation of mechanical performance of high impact strength aramid/glass fiber-reinforced hybrid composites(İdris Karagöz, 2026) Arı, Büşra; Yüksel, Ayten; Bedeloğlu, AyşeThe internal structures of composites are damaged and therefore their strength decreases significantly, as they are exposed to impact. For this reason, hybrid composite materials containing different types of fiber reinforcements or nanomaterials that are more resistant to mechanical loads are currently being studied. In this study, due to its advantages such as low weight and high strength, aramid/glass fiber reinforced layered hybrid composite plates were produced by vacuum infusion method by adding nano graphene powder into epoxy resin at different weight ratios (0 wt %, 0.20 wt % and 0.25 wt %). The mechanical properties (tensile, three-point bending and impact tests) of the prepared composite test samples were tested. It was observed that the addition of nano graphene powder to layered aramid and glass fiber epoxy composites was effective in increasing the strength of the material. The nano graphene powder added glass and aramid fiber reinforced hybrid composite used at the most ideal values showed an increase of approximately 19.1% in impact strength, 6.4% in tensile strength and 20.4% in bending strength compared to the composite without additive.Öğe Mechanical properties of thermoplastic filament stitched carbon fiber reinforced composites(Bursa Teknik Üniversitesi, 2022) Sağlam, Gökçenur; Bedeloğlu, AyşeIn recent years, the use of composites has attracted great interest in both academia and industry, especially due to their lightness and mechanical properties. In this study, acrylonitrile butadiene styrene (ABS), poly(ethylene-co-methacrylic) acid (EMAA) and ethylene vinyl acetate (EVA) filaments were produced in a single screw extruder. The produced filaments were integrated into composite materials by stitching method, and then, the mechanical properties of the filaments and composites were investigated. According to the tensile test results, it is concluded that the stitching process affects the mechanical properties of the composite material. The strength of the composite material produced with EVA filament with a maximum diameter of 1mm increased by 23%. Apart from these, the composite materials produced with 1mm ABS and 0.6mm and 0.8mm EMAA filaments increased by an average of 15%. There was no significant change in the elongation of the composite material produced with 0.6mm, 0.8mm, and 1mm diameter filaments. The elongation of the composite material produced with only 1mm diameter ABS filament increased by 12%. The elongation values of the composite material prepared with 0.6mm diameter EMAA and EVA polymers decreased also by 15%.Öğe Nanomaterials with potential EMI shielding properties(2019) Altın, Yasin; Bedeloğlu, AyşeNanomaterials exhibit unexpected superior properties such as electrical, magnetic, optical, etc., compared with bulk materials. In this chapter, electromagnetic interference (EMI) shielding properties of different nanomaterials based on metal, metal oxide, ceramic, conductive polymer-modified, and their hybrids are reviewed. The effects of size, shape, structure, and morphology of nanomaterials on EMI shielding properties were also discussed. EMI shielding is mainly realized by three mechanisms, which are absorption, reflection, and multiple reflections. In recent years, academic studies have mostly focused on hybrid nanostructures, which often combine absorption and reflection properties. Meanwhile, an evaluation covering most of the important advancements related to nanomaterials with potential EMI shielding properties is also provided.Öğe ORGANİK FOTOVOLTAİK TEKNOLOJİSİ VE TEKSTİL UYGULAMALARI(Isparta University of Applied Sciences, 2023) Tacer, Buket Turak; Bedeloğlu, Ayşe; Selbaş, ReşatFotovoltaik, güneş ışığına maruz kaldığında, gerilim farkı yapabilme kabiliyeti olarak tanımlanabilmektedir. Fotovoltaik güneş pilleri de 1. Nesil, 2. Nesil ve 3. Nesil olarak sınıflandırılmaktadır. 1. Nesil piller pahalı, sert, üretimi çok enerji gerektiren, 2. Nesil piller ise yüksek sıcaklık gerektiren üretim tekniklerine sahip pillerdir. Ancak 3. Nesil güneş pillerinden biri olan organik güneş pilleri, polimer esaslı olup, esnek ve maliyeti düşük pillerdir. Bu çalışma kapsamında da fotovoltaik teknolojisi ve organik fotovoltaik (OPV) güneş pilleri incelenmiş olup, pillerin güç dönüşüm verimliliklerini hesaplamak için kullanılacak parametrelerden bahsedilmiştir. Araştırmaların gittikçe yoğunlaştığı esnek organik güneş pillerinden biri olan giyilebilir tekstil esaslı organik güneş pillerinden de bahsedilmiş olup, araştırmacıların yaptıkları çalışmalara yer verilmiştir. Çalışma sonucunda, tekstil esaslı organik güneş pillerinin güç dönüşüm verimlilik değerlerinin henüz inorganik güneş pillerinin verimlilik değerleri kadar yüksek değerlere ulaşamadığı, ancak gün geçtikçe verim iyileştirme çalışmalarının devam ettiğini görmekteyiz.Öğe Polyacrylonitrile Nanofiber Optimization as Precursor of Carbon Nanofibers for Supercapacitors(Bursa Teknik Üniversitesi, 2020) Altın, Yasin; Bedeloğlu, AyşePolyacrylonitrile (PAN) nanofibers are one of the primary precursors in the production of carbon nanofibers. The nanofiber morphology is significantly affected by the process parameters such as polymer concentration, distance, applied voltage and feed rate during the production of PAN nanofibers obtained by the solution-based electrospinning method, and these parameters should be optimized properly. In this study, firstly PAN nanofiber production parameters were optimized, and then homogeneous and thin PAN nanofibers produced in optimum conditions were used as the precursor in the production of carbon nanofibers. PAN nanofibers with a diameter of 233 nm were obtained at 7.5% PAN concentration in N,N-dimethylformamide (DMF), 28 kV applied voltage, 17.5 cm nozzle to collector distance, 2 ml/h feed rate and 500 rpm rotation speed of the aluminum drum. The carbon nanofiber diameters produced after the stabilization and carbonization processes were measured as 200 and 140 nm, respectively. The morphological, chemical and thermal properties of the produced nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR), thermogravimetric analyzer (TGA). Carbon nanofibers, which are made from optimized electrospun PAN nanofibers, can be used to construct supercapacitors in future studies.Öğe Self-Healing Carbon Fiber Composites with Thermoplastic Polymers(Bursa Teknik Üniversitesi, 2022) Sağlam, Gökçenur; Bedeloğlu, AyşeThe utilization areas of composite materials are increasing day by day. However, these materials are difficult and expensive to manufacture. In addition, since they are thermoset structures, their recycling is very limited in case of damage. Self-healing materials are the ones that automatically and independently heal or repair the damage caused by any factors, without external intervention. Self-healing polymeric materials are in the range of smart materials. Research on self-healing polymers and polymer composites using this effect has increased rapidly in recent years due to the advantages such as cost reduction and less labour requirement that the current topic provides. In this review, first of all, brief information about self-healing mechanisms used in composites will be given in the light of the studies in literature, then the use of stitch method in composites and self-healing composites will be mentioned and finally, the test methods of self-healing composites will be addressed.Öğe STRETCHABLE PIEZORESISTIVE SENSORS WITH GRAPHENE AND POLYANILINE COATED WOVEN POLYESTER FABRICS(Eskişehir Teknik Üniversitesi, 2021) Çetinoğlu, Meryem; Fındık, Gizem; Ünsal, Ömer Faruk; Bedeloğlu, AyşeStrain is the concept that expresses how much a material changes its shape under mechanical action. Strain sensors are smart materials that can be used in mechanical characterization, structural quality control and, more recently, wearable electronics. In the literature, there are studies that can detect strain by using a piezoresistive mechanism. Piezoresistive effect defines the electrical conductivity (or resistivity) changes of a material under mechanical stress. The developed fabric strain sensor can be used in smart textiles and future applications for wearable electronics.Öğe WEARABLE TEXTILE-BASED PIEZOELECTRIC NANOGENERATORS WITH GRAPHENE/ZNO/AgNW(Eskişehir Teknik Üniversitesi, 2021) Demir, Emre; Ünsal, Ömer Faruk; Emiroğlu, Filiz; Bedeloğlu, AyşeWhile people are dealing with problems such as carbon footprint, water, air and environmental pollution and global warming caused by the use of traditional fossil energy sources, they have also faced the dilemma of energy crisis in search of alternative renewable energy sources. It is becoming more and more important to develop alternative energy sources such as wind, solar and tidal energy, renewable and clean energy. In addition to these, nanogenerators, which convert waste mechanical energy into electrical energy by physical interaction, have attracted great attention among innovative studies in recent years. Maintenance-free and flexible wearable nanogenerators using a sustainable power source are being developed for wearable/portable electronics. In this study, thermoplastic polyurethane coated nanogenerator fabrics containing graphene/ZnO/AgNw were developed for use in wearable electronics and the effect of zinc oxide concentration on the output power of textile-based nanogenerators was investigated. As a result, the nanogenerator produced with the mixture using 7% ZnO produced 10 mW of power, thus showing that ZnO-based materials can help the development of flexible piezoelectric TPU-based nanogenerators and advance to a new stage.Öğe Başlıksız(Springer International Publishing Ag, 2021) Hicyilmaz, Ayse Sezer; Bedeloğlu, AyşePolyimides, high-performance polymers with superior properties such as high temperature stability, resistance to solvents and high strength, can be used in high-tech applications of the aerospace and aviation, medical or electronics industry in different forms (film, fiber, nanofiber, membrane, foam, adhesive or coating). Among these applications, coating has a special place and is used to develop advanced structures having high temperature resistance, flame retardancy and etc. for high tech industries via an economical and feasible way. Therefore, in this review, we aimed to report the broad application status of polyimide coatings by reviewing publications, patents and commercial products. Thus, this study can assist in selecting suitable polyimide types and production methods for polyimide coating applications and in understanding their applicability for future products.Öğe Başlıksız(Sage Publications Ltd, 2022) Hicyilmaz, Ayse Sezer; Bedeloğlu, AyşeIn this study, ethylene vinyl acetate (EVA) transparent nanocomposite films, which heal easily with the inclusion of a low amount of silver nanowire (AgNw), were produced. For this purpose, first AgNw was homogeneously dispersed in the polymer solution and then, nanocomposite films were produced from the solutions by casting method. The thermal, mechanical and optical properties of the produced films were characterized. Self-healing properties of nanocomposite films were confirmed by optical microscopy and mechanical tests. Optical microscope results showed that the optimum recovery temperature was 130 degrees C and the addition of a small amount (5% w/w) of AgNw reduced the recovery time of the scratch on EVA film reducing the healing time by 66.66% (from 15 minutes to 5 minutes). In addition, tensile test results supported the optical microscope results. DSC results showed that the regular crystal regions were formed in composite films due to the high thermal conductivity and nucleating agent effect of AgNw. On the other hand, DSC curves proved that the healing process was occurred via re-entanglement of the polymer chains by heat effect, while silver nanowire addition did not affect the mechanical strength and transparency of the films, significantly. AgNw-loaded-EVA-based self-healing transparent films can be used for applications such as tempered glass laminates, electrical cables, coatings, packages, especially to protect the product and reduce the cost of repair.Öğe Başlıksız(Sage Publications Ltd, 2020) Borazan, Ismail; Bedeloğlu, Ayşe; Demir, AliIn this article, the improvement in electrical performance of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as the transparent electrode doped with different additives (ethylene glycol (EG), isopropyl alcohol) or treatment of sulfuric acid was enhanced that organic solar cells (OSCs) were produced by using poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl C-61 butyric acid methyl ester. OSCs were fabricated by the doped or treated PEDOT:PSS films as transparent electrodes. The photoelectrical measurements were carried out and the effects of doping or treatment were compared. As a result, EG-added PEDOT:PSS electrode showed the best power conversion efficiency value of 1.87% among the PEDOT:PSS anodes.Öğe Başlıksız(Sage Publications Inc, 2022) Borazan, Ismail; Bedeloğlu, Ayşe; Demir, AliSolar energy is one of the most popular energy sources among the other renewable energies. Photovoltaic technology is a clean way to generate electricity from sunlight. Flexible photovoltaics enable portable electronic devices to power at off-grid conditions. Stainless steel mesh fabric was used as a substrate and electrode allowing the light to reach the photoactive layer. The photoactive layer and hole transport layer were deposited by the means of dip-coating like in the textile industry. The metal back electrode was evaporated in a thermal evaporator under vacuum. Promising results were obtained from photovoltaic measurements. About 0.69% power conversion efficiency was obtained from textile-based solar cells in this study. The textile-based metal fabric enables a flexible photovoltaic structure that can be integrated on non-planar surfaces to generate electricity, and also mesh structure allows the light to reach the photoactive layer.Öğe Başlıksız(Walter De Gruyter Gmbh, 2020) Terzioğlu, Pınar; Altin, Yasin; Kalemtaş, Ayşe; Bedeloğlu, AyşeRecently, due to sustainable development and environmental protection policies, there is increasing interest in the development of new biodegradable polymer-based multifunctional composites. Chitosan is one of the most remarkable and preferred biopolymers, which is environmentally friendly as well as renewable, biocompatible, and inexpensive. Though it has a wide range of potential applications, the major limitation of chitosan - the problem of poor mechanical performance needs to be solved. In this work, graphene oxide was first produced and then used to manufacture a chitosan/graphene oxide/zinc oxide composite film through a casting method. The properties of the chitosan film and the chitosan/graphene oxide/zinc oxide composite film were investigated using Fourier transform infrared spectroscopy, mechanical, thermal gravimetric, and ultraviolet (UV)-visible spectroscopy analyses. The results showed that the incorporation of graphene oxide and zinc oxide into the chitosan matrix resulted in enhanced mechanical properties and thermal stability of chitosan biocomposite films. The graphene oxide- and zinc oxide-reinforced chitosan film showed 2527 MPa and 55.72 MPa of Young's modulus and tensile strength, respectively, while neat chitosan showed only 1549 MPa and 37.91 MPa of Young's modulus and tensile strength, respectively. Conversely, the addition of graphene oxide decreased the transmittance, notably in the UV region.Öğe Başlıksız(Walter De Gruyter Gmbh, 2019) Bedeloğlu, Ayşe; Cin, Zeynep IslekPolymer-based nanofibers are good candidates for medical textiles due to their excellent properties including high surface area, breathability and flexibility. Doping polymer nanofibers with different nanoparticles enhances their existing properties. In this study, electrospun polyamide 6,6 (PA6,6) composite nanofibers containing ZnO nanoparticles (<50 nm) in different amounts (1%, 3% and 5%) were first produced by electrospinning technique; then, these nanofibers were coated with sol-gel ZnO solution (0.5 M) via dip coating method at 1000, 3000 and 5000 mu m/s speeds. The sol-gel coating process increased the breaking strength of nanofiber mats, while the incorporation of ZnO nanoparticles into the polymer nanofibers reduced. Compared to pure PA6,6 nanofiber mats, the ZnO sol-gel coated samples and doped nanofibers had lower reflectance values. In addition, the reflection values decreased as the additive and coating speed increased.Öğe Başlıksız(Wiley, 2020) Unsal, Omer Faruk; Altin, Yasin; Bedeloğlu, AyşeRecently, piezoelectric nanogenerators have received great interest as they can convert waste mechanical and radiative energy to electricity and can be used in self-energy generating systems and sensor technologies. In this study, electrospun poly(vinylidene fluoride) (PVDF) nanofiber-based piezoelectric nanogenerators with reduced graphene oxide (rGO), polyaniline (PANI), and PANI-functionalized rGO (rGOPANI) have been developed. Two different types of nanofiber mats were produced: First, rGO- and rGOPANI-doped PVDF nanofiber mats and second, rGO, PANI and rGOPANI-spray-coated PVDF nanofiber mats that have worked as nanogenerators' electrodes. Then, characterizations of samples were performed in terms of piezoelectricity, Fourier transform infrared (FTIR) spectrophotometric, X-ray diffractions (XRD), and scanning electron microscopy analyses. FTIR and XRD results confirmed that piezoelectric beta-crystalline phase of PVDF occurred after the electrospinning process. Besides, maximum output voltages were obtained as 7.84 and 10.60 V for rGO-doped PVDF and rGOPANI-coated PVDF nanofiber mats, respectively. As a result, the doped nanofibers were found to be more successful due to the higher device accuracy in sensor technologies compared with spray-coated samples. However, spray-coating method proved to be more suitable technique for the production of nanogenerators on an industrial scale in terms of fast and large-scale applicability. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48517.Öğe Başlıksız(Walter De Gruyter Gmbh, 2019) Borazan, Ismail; Altin, Yasin; Demir, Ali; Bedeloğlu, AyşePolymer-based organic solar cells are of great interest as they can be produced with low-cost techniques and also have many interesting features such as flexibility, graded transparency, easy integration, and lightness. However, conventional wide bandgap polymers used for the light-absorbing layer significantly affect the power conversion efficiency of organic solar cells because they collect sunlight in a given spectrum range and due to their limited stability. Therefore, in this study, polymers with different bandgaps were used, which could allow for the production of more stable and efficient organic solar cells: P3HT as the wide bandgap polymer, and PTB7 and PCDTBT as low bandgap polymers. These polymers with different bandgaps were combined with PCBM to obtain increased efficiency and optimum photoactive layer in the organic solar cell. The obtained devices were characterized by measuring optical, photoelectrical, and morphological properties. Solar cells using the PTB7 and PCDTBT polymers had more rough surfaces than the reference cell using P3HT. The use of low-bandgap polymers improved I-sc significantly, and when combined with P3HT, a higher V-oc was obtained.Öğe Başlıksız(Wiley, 2019) Hicyilmaz, Ayse Sezer; Altin, Yasin; Bedeloğlu, AyşeMultifunctional technical textiles are of great interest both by industry and academia and these products are considered as high value-added products that contribute to the economies of countries. In this study, polyamic acid (PAA) was synthesized through polycondensation of pyromellitic dianhydride (PMDA) and 4,4 '-oxydianiline (ODA) in dimethyl acetamide (DMAc) at low temperature. Then, PAA was coated onto woven cotton and polyester fabric by padding technique. Finally, polyimide (PI)-coated multifunctional cotton and polyester fabrics were obtained by an easy coating technique and low-temperature imidization. Thus, low cost, easily accessible and widely used cotton and polyester fabrics were converted to high-performance textile products, which are flame retardant, UV protective, acid resistant, and waterproof. The chemical, thermal, morphological, optical, mechanical, wettability, chemical resistance, and flame retardancy properties of developed fabrics were investigated. Optical results showed that both PI-coated cotton and polyester fabrics are UV-A protective compared to noncoated fabrics. Moreover, PI-coated samples have high contact angles which are 111.43 degrees and 113.40 degrees for PI-coated cotton (PI-c-C) and PI-coated polyester (PI-c-PET), respectively. Young's modulus of PI-c-PET fabrics increased four times more than noncoated polyester fabric. PI coating changed the burning behavior of both cotton and polyester fabrics in a positive way. All the test results showed that these developed multifunctional textile products might find an application in different industrial areas such as automotive, aerospace, protective clothing, and so on due to easy and inexpensive production techniques and also superior properties. (c) 2019 Wiley Periodicals, Inc.Öğe Başlıksız(Elsevier Science Sa, 2019) Tas, Mahmut; Altin, Yasin; Bedeloğlu, AyşeIn this study, an environmental and economical multi-step reduction method has been developed for the reduction of graphene oxide thin films more efficiently. Within the scope of the method, the graphene oxide films produced were subjected to the process of chemical reduction with L-ascorbic acid (Vitamin C) as the first step and then to the process of thermal reduction that can be performed through progressive thermal annealing without any need for special atmospheric conditions as the second step. In addition, the impact of L-ascorbic acid solutions with different molarities (5, 25, 50, 100, 200, 400 and 800 mM) on the conductivity of the reduced graphene oxide produced was examined and compared with hydrazine hydrate for the same concentrations. Besides, the impact of different thermal annealing temperatures (70 degrees C, 120 degrees C and 300 degrees C) and the process of intermediate drying on the conductivity of the reduced graphene oxide thin films were investigated. The results show that the graphene oxide thin films were best reduced through 800 mM L-ascorbic acid and progressive thermal annealing combination (at 70 degrees C, 120 degrees C and 300 degrees C respectively) and that 13.2 k Omega/sq. surface resistivity was achieved and that the intermediate heating at 120 degrees C made at least 10% positive contribution to this.
- «
- 1 (current)
- 2
- 3
- »
