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Öğe Characterization of styrene butadiene rubber and microwave devulcanized ground tire rubber composites(Walter de Gruyter GmbH, 2014) Karabörk, Fazliye; Pehlivan, Erol; Akdemir, AhmetGround tire rubber (GTR) was devulcanized by microwaves at the same heating rate (constant power) and different times of exposure. The devulcanized rubber (DVR) and untreated GTR were characterized physically and thermally. Composite materials were prepared from different proportions of the GTR, which was used as a filler, and the DV-R, which was used as part of the styrene butadiene rubber (SBR) matrix, and by varying the exposure time of the microwave power. These composites were compared with a control sample that was prepared from virgin SBR. The sol content (soluble part) and Fourier transform infrared spectroscopy (FTIR) analyses of the devulcanized samples were examined to define the efficiency of devulcanization. The cure characteristics and tensile properties of the SBR composites were researched. In this study, it was found that using DV-R as part of the rubber matrix produced much better properties than using GTR as a filler, thereby showing the significant benefits of microwave devulcanization. At the DV-R content of 50 phr, the elongation at break of the DV-R 5 min/SBR composites increased to 445.06% from 217.25% for the GTR/SBR composites, i.e., the elongation at break was enhanced by 105% by the devulcanization of GTR. Scanning electron microscopy (SEM) photographs displayed a better interface coherence between the DV-R 5 min and SBR matrix than the GTR/SBR composites.Öğe Effect of Silica/Graphene nanohybrid particles on the mechanical properties of epoxy coatings(Springer Berlin Heidelberg, 2019) Özcan, Ümit Esra; Yazman, Şakir; Akdemir, Ahmet; Karabörk, FazliyeEpoxy resins are used as coating materials, but the practical use of epoxy coatings in industries is limited due to their weak mechanical properties. In the present paper, different amounts of silica nanoparticles ( SiO2) and graphene nanoplatelets (GNPs) were introduced separately and together into an epoxy coating matrix as reinforcements. Graphene, a newly discovered carbon allotrope, has been found to improve the mechanical properties of the polymer composites in which it is dispersed. Silica particles are also known to improve the mechanical properties of composites. In this study, mechanical, physical and thermal properties of the epoxy coatings are considered as multidimensional by the macro- and microanalyses. The experimental results showed that after the addition of GNPs into the epoxy matrix, the flexibility and impact resistance of the coatings increased by 8.3 and 157.1%, respectively, in relation to neat epoxy. The microhardness increased by 53.8% and penetration depth, which is indicative of the scratch resistance, decreased by 29.7%, with the addition of SiO2 –GNPs nanohybrid. A remarkable synergistic effect was observed between the GNPs and SiO2 , which improved the hardness and the scratch resistance of the epoxy coatings.Öğe Effects of nano reinforcing/matrix interaction on chemical, thermal and mechanical properties of epoxy nanocomposites(SAGE Publications Ltd, 2021) Yazman, Şakir; Uyaner, Mesut; Karabörk, Fazliye; Akdemir, AhmetThis article investigates the impact of addition various types of nanoparticles with different structural, dimensional, and morphological properties on the interphase region formed between the particle/matrix and the curing behavior of the epoxy affect the nanocomposite material properties. For this purpose, epoxy nanocomposites (NCs) were produced by adding multi-walled carbon nanotube (MWCNT) and alumina (Al2O3) nanoparticles (NPs) into the epoxy matrix at different rates (0.5–2.0 wt.%). The effects of the particle/matrix interaction on the properties of the composite have been revealed by chemical, thermal, mechanical analyzes and microstructure investigations. An increase in the absorption density, which reveals the physical interaction of nanoparticles with the epoxy matrix, was observed in Fourier-transform infrared spectroscopy. Absorption vibration peak intensities in nanocomposite samples were at most 1.0 wt.% Al2O3 and 1.25 wt.% CNT added nanocomposites. It was observed that the Tg value increased depending on the number of nanoparticles. The addition of Al2O3 increased Tg values more than CNT. Besides, the mechanical properties of NCs were determined by tensile tests. The highest increase in mechanical properties was achieved by adding 1.25 wt.% CNT and 1.0 wt.% Al2O3, respectively. Mechanical properties tended to decrease at higher addition rates. The shape, size, amount, and distribution of nanoparticles added into the epoxy matrix directly affected the NCs' properties. It has been determined that homogeneously dispersed spherical Al2O3 nanoparticles are more effective than fiber-shaped CNTs in the properties of NCs.Öğe Farklı oranlarda DPDS kullanılarak devulkanize edilmiş atık taşıt lastikleri ilave edilen SBR malzemenin mekanik özelliklerinin incelenmesi(Pamukkale Üniversitesi, 2015) Karabörk, Fazliye; Akdemir, AhmetOda sıcaklığında öğütülen atık taşıt lastiği tozu mikrodalga yöntemiyle devulkanize edilmiştir. İşlemde devulkanizasyon ajanı olarak, kükürt bağlarının (S-S) koparılmasında etkinliği çeşitli çalışmalarda ortaya konulmuş olan, DPDS (difenildisülfür) kullanılmıştır. Mikrodalga gücü sabit tutularak, zamanın ve DPDS miktarının prosese etkileri incelenmiştir. İşlem görmemiş atık lastik tozu fiziksel ve termal olarak karakterize edilmiştir. 20 phr oranında atık lastik tozu ve aynı oranda devulkanize kauçuk (DVR) stiren bütadien kauçuğa (SBR 1723 ve SBR 1502) katılarak kompozit malzemeler hazırlanmıştır. Bu kompozitler orijinal SBR'den hazırlanan kontrol numunesiyle karşılaştırılmıştır. Devulkanizasyonun etkinliğini ortaya koyabilmek için devulkanize numunelerin çözünme oranları (sol content) belirlenmiş ve Fourier Transform Infrared Spektrofotometre (FTIR) analizi yapılmıştır. Elde edilen kompozit malzemelerin mekanik özellikleri incelenmiştir. Çalışmada, DVR katılan malzemelerde atık lastik tozu katılan malzemelere göre daha iyi devulkanizasyonunun önemli avantajlar sağladığını göstermiştir. Kopma uzaması değeri, işlem görmemiş atık lastik tozu katılan kompozit malzemede %481 iken, 1 g DPDS katılarak 4 dk. süreyle devulkanize edilen kauçuğun katıldığı DVR/SBR kompozitte %578 olarak elde edilmiştir, böylece kopma uzaması değeri atık lastik tozunun devulkanizasyonuyla %20 oranında artmıştır.Öğe Friction and wear behavior of styrene butadiene rubber-based composites reinforced with microwave-devulcanized ground tire rubber(John Wiley and Sons Limited, 2015) Karabork, Fazliye; Akdemir, AhmetIn this work, the tribological properties of a new material obtained by revulcanization with styrene butadiene rubber (SBR)and devulcanized ground tire rubber (GTR) were investigated. GTR was devulcanized using the microwave method at a constant powerwhile varying the microwave exposure time. Devulcanized rubber (DV-R) and untreated GTR were revulcanized by mixing with SBR atdifferent rates (10, 30, 50 phr). To determine friction and wear characteristics of the samples, pin (ball) on disc and abrasion tests wereconducted. Scanning electron microscopy (SEM) was employed to observe the worn surfaces of the composites to correlate the experi-mental test results to the wear mechanisms. All of these tests and experiments were performed on original vulcanized rubber samplesfor comparison. The composites exhibited different friction and wear behavior due to morphology, dispersion behavior and devulcaniza-tion functionalization of ground tire rubber. In general, DV-R/SBR composites exhibited improvement in both mechanical and tribolog-ical properties. However, the enhanced compatibility of DV-R resulting from the specific chemical coupling of DV-R with SBR wascrucial for the mechanical, friction and wear properties.VC2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132,42419Öğe Improvement of anti-corrosion performance (surface and near the cut edge) and mechanical properties of epoxy coatings modified with nano, micro and hybrid ZnO particles(SAGE Publications Ltd, 2023) Kabaoğlu, Emre; Karabörk, Fazliye; Balun Kayan, Didem; Akdemir, AhmetComposites were formed by incorporating nano, micro and hybrid-ZnO particles into the epoxy matrix at the same loading levels (3%) and applied at 90 ?m thickness on the galvanized steel substrate using a film applicator in this study. The improvement in anti-corrosion performance and mechanical and physical properties of the composite coatings were evaluated using various tests and techniques such as salt-spray, electrochemical impedance spectroscopy, nanohardness, microscratch, cross-cut, bending, Fourier transform infrared spectroscopy, thermogravimetric and Scanning electron microscopy. The corrosion performance of the composite coatings near the cut edge is discussed in detail as well as on the surface of galvanized steel. The results show that the addition of all ZnO particles has a positive effect on the corrosion resistance and mechanical properties of the coatings. The addition of nano, micro and hybrid ZnO particles increased the hardness of the composites by 52, 37 and 56%, respectively, compared to the neat epoxy. Although the cathodic protection performance is weakened near the cut edge due to the loss of Zn after thermal cutting, high barrier protection was provided with composite coatings, especially micro ZnO/Epoxy composite coating.Öğe Investigation effect of zinc nanoparticles on the mechanical and anticorrosion properties of epoxy coatings on stainless steel surface(Gazi Üniversitesi, 2021) Apsak, Merve; Akdemir, Ahmet; Karabörk, Fazliye; Yazman, ŞakirIn this study, effects of zinc nanoparticles (ZNPs) on the mechanical properties of epoxy coatings and anticorrosion behavior on the stainless steel were investigated. The nanocomposites (NCs) were obtained by adding ZNPs (0.5, 1.0, 1.5 wt%) to epoxy resin. The first stage in this study, bulk samples were prepared for tensile test and DSC, TGA, FTIR, SEM analysis. The test and analysis were performed separately for samples cured at room temperature for 24 h and postcured at 80 degrees C for 15 h in the oven. The results indicated that both postcuring and adding ZNPs caused an increase in the mechanical properties of the epoxy matrix. Tensile strength increased by 13.2% and 90.2% in the postcured NC (1.0% Zn) and untreated NC (0.5% Zn) respectively. The NCs prepared with the same parameters for the second stage were coated on AISI 304 test panels and the panels were postcured in the oven. The anticorrosive performance of the coatings was studied by an immersion test. According to the corrosion test results, it was observed that the coated steel surface preserves the best rate of 1.0% ZNPs containing epoxy composite. In addition, impact resistance, flexibilities and adhesion properties of the coating were analyzed.Öğe Investigation of mechanical properties of SBR in which added devulcanized waste tire rubber with various proportions of DPDS(Pamukkale University, 2015) Karabörk, Fazliye; Akdemir, AhmetThe waste tire rubber that had been grounded in room temperature was devulcanized by using the microwave method. As the devulcanizing agent, diphenyldisulfide (DPDS), the efficiency of which in the breaking off of sulfur bonds (S-S) had been proven in various studies, was employed. By maintaining the microwave power at a fixed value, the effects of time and the DPDS amount on the process were investigated. The untreated waste tire rubber powder was characterized physically and thermally. Composite materials were prepared with 20 phr untreated waste tire rubber powder and devulcanized rubber (DVR) with the styrene butadiene rubber (SBR) matrix. These composites were compared with a control sample that was prepared from virgin SBR. The sol content (soluble part) and Fourier Transform Infrared Spectrophotometer (FTIR) analyses of the devulcanized samples have been examined to define the efficiency of devulcanization. The mechanical properties of the SBR composites were researched. In this study, it was found that using devulcanized rubber produced much better properties than using waste tire rubber powder, thereby showing the significant benefits of microwave devulcanization. At the DPDS content of 1 g, the elongation at break of the DVR 4 min/SBR composites increased to 578% from 481% for the untreated waste tire rubber powder and SBR composites, the elongation at break was enhanced by 20% by the devulcanization of waste tire rubber powder.Öğe Nano çinko oksit partikül katılan epoksi kaplamaların mekanik ve antikorozif özelliklerinin incelenmesi(Uludağ Üniversitesi, 2023) Askerden, Mehmet Kubilay; Akdemir, Ahmet; Karabörk, Fazliye; Yazman, ŞakirBu çalışmada, metal yüzeyleri korumak amacıyla kullanılan epoksi kaplamaya katılan ZnO nanopartiküllerin kaplamanın mekanik ve antikorozif özellikleri üzerindeki etkisi araştırılmıştır. Çalışma iki aşamada gerçekleştirilmiştir. İlk aşamada hem katılacak partikül miktarını belirleyerek kompozit malzemeyi üretmek hem de bu malzemenin özelliklerini belirlemek için çalışmalar yapılmıştır. Deneysel çalışmalar sonucunda epoksi matrise ağ. %0,5, 1 ve 1,5 oranlarında nano ZnO katılmasına karar verilmiştir. Bu oranlarla hazırlanan kompozit malzemelere uygulanan çekme testi sonunda en yüksek özellikler ağ. %1 ZnO nanopartikül katılan kompozit malzemede elde edilmiştir. Nanokompozitlerin diğer özelliklerini belirlemek amacıyla ayrıca; DSC, TGA, FTIR, SEM analizleri yapılmıştır. İkinci aşamada hazırlanan nanokompozitler çelik test plakaları üzerine kaplanmıştır. Kaplamaların antikorozif performansı asit çözeltisine daldırma ve tuz sisi testleri ile incelenmiştir. Korozyon testi sonuçlarına göre, en iyi sonuç %1 ZnO nanopartikül katılan kompozit kaplamada elde edilmiştir. Ayrıca kaplamaların darbe dayanımı, esnekliği ve çelik alt tabakaya yapışma özellikleri çeşitli testlerle incelenmiştir.Öğe Preparation of gadolina stabilized bismuth oxide doped with boron via electrospinning technique(Springer, 2012) Tunç, Tuncay; Uslu, İbrahim; Durmuşoğlu, Şenol; Keskin, Selda; Aytimur, Arda; Akdemir, AhmetIn this study, boron doped and undoped poly (vinyl) alcohol/bismuth-gadolina acetate (PVA/Bi-Gd) nanofibers were prepared using electrospinning technique then calcinated at 800 degrees C for 2 h. The originality of this study is the addition of boron to metal acetates. The effects of boron doping were investigated in terms of solution properties, morphological changes and thermal characteristics. The characteristics of the fibers were investigated with FT-IR, XRD, SEM and BET. The addition of boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers. XRD analyses showed that boron doping increased the peak intensities and indicated that the boron doping enhanced the crystallite size. Moreover, no shifts were noticed in diffraction angles for boron doped and undoped samples. Therefore, boron doping did not significantly alter the lattice spacing. The SEM micrograph of the fibers showed that the addition of boron resulted in the formation of cross-linked bright-surfaced fibers. The average fiber diameter for boron doped and undoped fiber mats were 204 and 123 nm, respectively. Also, grain diameters of boron doped and undoped nanocrystalline sintered powders were measured as 140 and 118 nm, respectively. The BET results showed that boron undoped and doped Bi2O3-La2O3 nanocrystalline powder ceramic structures sintered at 800 degrees C have surface areas of 59.72 and 39.80 m(2)/g, respectively.Öğe Synthesis and characterization of boron-doped Bi2O3-La2O3 fiber derived nanocomposite precursor(Springer, 2011) Durmusoğlu, Şenol; Uslu, İbrahim; Tunç, Tuncay; Keskin, Selda; Aytimur, Arda; Akdemir, AhmetBoron doped poly(vinyl) alcohol/ bismuth - lanthanum acetate (PVA/Bi-La) nanofibers were prepared by electrospinning using PVA as a precursor. The effect of boron doping was investigated in terms of solution properties, morphological changes and thermal characteristics. The fibers were characterized by FT-IR, XRD, SEM and BET. The addition of boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers. XRD analyses showed that boron doping increased the peak intensities and indicated that the boron doping enhanced the crystallite size. Moreover, no shifts were noticed in diffraction angles for boron doped and undoped samples. Therefore, boron doping did not significantly alter the lattice spacing. The SEM micrograph of the fibers showed that the addition of boron resulted in the formation of cross linked bright surfaced fibers. Also, grain diameters of boron doped and undoped nanocrystalline sintered powders were measured as 170 nm and 120 nm respectively. The BET results show that boron undoped and doped Bi2O3-La2O3 nanocrystalline powder ceramic structures sintered at 800 A degrees C have surface areas of 20.44 m(2)/g and 12.93 m(2)/g, respectively.
