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Öğe Anti-wear behaviour of silver nanoparticles on Al-Si alloy(Iop Publishing Ltd, 2021) Akgul, Yasin; Simsir, HamzaIn recent years, studies have shown that using nanoparticles (NPs) as lubricant additives lead to the enhancement of the anti-wear behaviour of oils. In this study, the anti-wear behaviour of silver (Ag) NPs which were capped with polyvinyl alcohol and sodium citrate were investigated for three different sliding speeds (2, 3 and 4 mm s(-1)) under two different loads (30 and 50 N). Results show that the AgNPs led to a decrease in friction and wear due to the formation of a tribofilm and a rolling effect. However, influence of the AgNPs declined at higher loads while increasing at higher speed test conditions. Also, both stabilising agents underwent disordering of AgNPs morphology and size successively under the applied loads.Öğe Biodegradable Biconstituent Melt-Blown Nonwovens for Air Filtration: Fabrication and Characterization(Korean Fiber Soc, 2024) Eticha, Andinet Kumella; Akgul, Yasin; Pakolpakcil, Ayben; Unlu, Oguz Kagan; Ahmed, Salih Birhanu; Cug, Harun; Kilic, AliMelt-blown polypropylene (PP) is extensively used in air filtration due to its low cost, low weight, and easy processing, but there are increasing environmental concerns due to its non-degradability. On the other side biodegradable polymers such as polylactic acid (PLA) present insufficient strength and limited toughness. Polymer blending is a well-known approach to reach optimum properties from at least two polymers. This study aims to produce biodegradable PP-PLA-based filter materials that possess enhanced elasticity and superior filtration performance. The addition of PLA raises the average fiber diameter (AFD), causing the PP-PLA filters to have AFD ranging from 0.73 to 0.91 mu m. However, the incorporation of zinc stearate (ZnSt) decreased the melt viscosity, resulting in thinner fiber formations with AFD ranging from 0.6 to 0.75 mu m for PP-PLA-ZnSt. The efficiency of the corona-charged optimized sample (double-layer 75PP-25PLA-ZnSt) showed 97.42% particle capture efficiency and filtration performance of 0.12 mmH(2)O(-1). Despite the presence of hydrophobic surfaces in all filter materials, the addition of ZnSt further improves the resistance to surface wettability. 75PP-25PLA-ZnSt filter material exhibits high stretchability, with a maximum tensile strength of 380 +/- 70 kPa. The proposed tricomponent (PP-PLA-ZnSt) approach would be used to reduce the environmental impact of non-degrading polymers.Öğe Centrifugally spun hydroxyapatite/carbon composite nanofiber scaffolds for bone tissue engineering(Iop Publishing Ltd, 2024) Akgul, Yasin; Stojanovska, Elena; Calisir, Mehmet Durmus; Polat, Yusuf; Kilic, AliIn recent years, advancements in tissue engineering have demonstrated the potential to expedite bone matrix formation, leading to shorter recovery times and decreased clinical challenges compared to conventional methods. Therefore, this study aims to develop composite carbon nanofibers (CNFs) integrated with nano-hydroxyapatite (nHA) particles as scaffolds for bone tissue engineering applications. A key strategy in achieving this objective involves harnessing nanofibrous structures, which offer a high surface area, coupled with nHA particles expected to accelerate bone regeneration and enhance biological activity. To realize this, polyacrylonitrile (PAN)/nHA nanofibers were fabricated using the centrifugal spinning (C-Spin) technique and subsequently carbonized to yield CNF/nHA composite structures. Scanning Electron Microscopy (SEM) confirmed C-Spin as a suitable method for PAN and CNF nanofiber production, with nHA particles uniformly dispersed throughout the nanofibrous structure. Carbonization resulted in reduced fiber diameter due to thermal decomposition and shrinkage of PAN molecules during the process. Furthermore, the incorporation of nHA particles into PAN lowered the stabilization temperature (by 5 degrees C-20 degrees C). Tensile tests revealed that PAN samples experienced an approximately 80% increase in ultimate tensile strength and a 187% increase in modulus with a 5 wt.% nHA loading. However, following carbonization, CNF samples exhibited a 50% decrease in strength compared to PAN samples. Additionally, the addition of nHA into CNF improved the graphitic structure. The incorporation of nHA particles into the spinning solution represents a viable strategy for enhancing CNF bioactivity.Öğe Centrifugally spun micro-nanofibers based on lemon peel oil/gelatin as novel edible active food packaging: Fabrication, characterization, and application to prevent foodborne pathogens E. coli and S. aureus in cheese(Elsevier Sci Ltd, 2022) Dogan, Nurcan; Dogan, Cemhan; Eticha, Andinet Kumella; Gungor, Melike; Akgul, YasinThis study aimed to develop innovative micro-nano fibers loaded with lemon peel essential oil for food packaging via centrifugal spinning. Lemon peel essential oil (LPO) was extracted from dried lemon peel by hydrodistillation. The major one of the 16 components of the extract detected by GS-MS was limonene (60.4%). Gelatin fibrous mats loaded with three different concentrations of LPO were fabricated with centrifugal spinning and then crosslinked. Micro-nanofibers were characterized in encapsulation efficiency, morphological, chemical, thermal, hydrophobicity and microbiological aspects. The in-vitro evaluation showed that the effect of fibers on grampositive Staphylococcus aureus (S. aureus) ATCC 29213, especially due to the antimicrobial activity of limonene, was greater than that of gram-negative Escherichia coli (E.coli) ATCC 35218. This effect was also consistent with the in-situ evaluation in which micro-nano fibers were applied to contaminated cheeses. Moreover, LPOloaded gelatin centrifugal spun positively affected the shelf life by suppressing the growth of aerobic mesophilic bacteria and yeast molds that cause spoilage in cheese.Öğe Centrifugally spun silica (SiO2) nanofibers for high-temperature air filtration(Taylor & Francis Inc, 2019) Tepekiran, Beyza Nur; Calisir, Mehmet D.; Polat, Yusuf; Akgul, Yasin; Kilic, AliIn this study, silica-based nanofibers were produced via centrifugal spinning (C-spin) and subsequent calcination. The produced heat resistant media was challenged with NaCl nanoparticles to investigate their filtration performance. To obtain inorganic SiO2 nanofibers, C-spun organic PVP-TEOS nanofibers were calcinated at 300-600 degrees C. Effects of solution concentration and calcination temperature on crystallinity, morphology and air filtration performance of nanofibers were investigated. Scanning electron microscopy (SEM) analysis was performed to analyze fiber diameter and morphology of nanofibrous webs. Differential thermal analysis (DTA) was realized for the thermal behavior of samples. Moreover, X-ray diffraction (XRD) and Fourier transform infrared spectra (FTIR) analysis were realized for further characterization. In addition to the chemical and morphological analysis, the ductility of the samples was investigated via tensile tests. Finally, calcinated webs were challenged with 0.4 mu m salt particles to analyze their filtration performance. The calcinated 5 wt% TEOS/PVP silica nanofiber webs were more brittle due to three times lower precursor content. Therefore, flexibility (percent elongation) of 15 wt%TEOS/PVP sample was nearly five times higher than 5 wt%TEOS/PVP sample. The calcinated 15 wt%TEOS/PVP sample showed the highest filtration performance among all the silica nanofibers. The average fiber diameter of the optimized web was found to be the lowest, which is around 521 +/- 308 nm, which resulted in enhanced filtration efficiency around 75.89%. Copyright (c) 2019 American Association for Aerosol ResearchÖğe Characterization of solution blown thermoplastic polyurethane nanofibers modified with Szygium aromaticum extract(Taylor & Francis Ltd, 2020) Canbay-Gokce, Emine; Akgul, Yasin; Gokce, Ahmet Yakup; Tasdelen-Yucedag, Cigdem; Kilic, Ali; Hassanin, AhmedAntibacterial wound dressing mats were produced via coating solution blown TPU nanofiber mats with Szygium aromaticum extract (clove oil). Soxhlet extraction was used to obtain clove oil (CO) and according to gas chromatography-mass spectrometry analysis, it was shown that extract was mostly composed of eugenol and beta-caryophylene, which exhibit superior antimicrobial activity. TPU nanofiber mats were coated with obtained clove oil in order to obtain antibacterial nanofibers. Even 2 mg/cm(2) clove oil coated TPU nanofibers (E2/TPU) exhibited a zone of inhibition around 24 and 22 mm against S. aureus and E. coli, respectively. On the other hand, air permeability of nanofibrous mats decreased with the increasing amount of clove oil over 5 mg/cm(2), because clove oil caused changes in nanofiber morphology. However, the presence of clove oil did not affect the morphology of E2/TPU, where air permeability values of those dressings were close to that of neat TPU nanofiber mats.Öğe The effect of GNPs on wear and corrosion behaviors of pure magnesium(Elsevier Science Sa, 2017) Turan, Muhammet Emre; Sun, Yavuz; Akgul, Yasin; Turen, Yunus; Ahlatci, HayrettinThis study aims to investigate the role of graphene on wear and corrosion behaviors of pure magnesium. Magnesium/Graphene Nanoparticle (GNP) composites were fabricated via semi powder metallurgy method with a different content of graphene (0.1, 0.25 and 0.5 wt%). The effect of graphene in pure magnesium was examined by hardness, wear and corrosion tests. Microstructural and phase analysis were carried out by Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) analysis. Experimental results revealed that, hardness values increased with the addition of graphene. There was a same trend in wear behaviors with increase of graphene rate. The best wear performance was belonging to the 0.50 wt% graphene/mg composite under load of 10N. So improvement of wear properties was achieved using graphene as reinforcement. According to the microstructural evolution, the uniform distribution was achieved for all samples but partially agglomeration could be seen in Mg-0.50 wt% graphene. Compared to the pure magnesium, corrosion performance was affected negatively in graphene reinforced composites. (C) 2017 Elsevier B.V. All rights reserved.Öğe Effect of TiC, TiN, and TiCN on Microstructural, Mechanical and Tribological Properties of PM Steels(Int Inst Science Sintering (I I S S), 2021) Erden, Mehmet Akif; Tasliyan, Mehmet Furkan; Akgul, YasinDevelopments in sintering of powder mixtures contributed growth of steel production via powder metallurgy. This study aims to improve the mechanical and tribological properties of carbon steels produced via powder metallurgy. For this purpose, P/M carbon steel was alloyed with 3 % Manganese. Then, this alloyed steel was reinforced with particles such as titanium carbide (TiC), titanium nitride (TiN) and titanium carbonitride (TiCN) in different proportions (0.5 and 1 %) and combinations. The effect of these additives on the mechanical properties of PM steels was determined by conducting tensile and hardness tests. Wear tests were performed to understand the tribological properties of samples. Also, microstructural properties, fracture surfaces, and worn surfaces of samples were examined using a Scanning Electron Microscope. Results show that the hardness and tensile strength of carbon steel increased by nearly 158 % and 62 % respectively, while the wear resistance improved by 4 times with the addition of 3 % Mn and 0.5 % TiCN.Öğe Electrically assisted solution blow spinning of PVDF/TPU nanofibrous mats for air filtration applications(Tubitak Scientific & Technological Research Council Turkey, 2023) Eticha, Andinet Kumella; Toptas, Ali; Akgul, Yasin; Kilic, AliIn this study, pure polyvinylidene fluoride (PVDF), pure thermoplastic polyurethane (TPU), and PVDF/TPU blend nanofibers (1:3, 2:2, 3:1 ratios) were produced via electrically assisted solution blow spinning for air filtration applications. Scanning electron microscopy (SEM) analysis was conducted to investigate the diameters and morphology of nanofibers. The filtration performance of nanofibrous mats was examined by air filtration test with challenging with 0.26 +/- 0.07 mu m salt particles. Moreover, the flexibility and strength of the samples were determined via tensile tests. Results showed that pure TPU nanofibers had better mechanical properties, while pure PVDF nanofibers showed better filtration performance. However, 3PVDF/1TPU nanofibrous sample had high filtration efficiency (98.86%) close to pure PVDF (99.85%) and better flexibility (32.80% elongation) compared to pure PVDF (11.64% elongation).Öğe Fabrication of stretchable and high-filtration performance melt-blown nonwoven webs for PM0.3 aerosol filtration(Wiley, 2024) Eticha, Andinet Kumella; Akgul, Yasin; Pakolpakcil, Ayben; Unlu, Oguz Kagan; Cug, Harun; Kilic, AliPolypropylene (PP) is a semi-crystalline polymer that displays simple manufacturing, high stiffness, lightweight, chemical resistance, and inexpensive. However, PP has significant drawbacks, such as poor brittleness at low temperatures, high shrinkage ratio, and low impact resistance, which limit its development. Thermoplastic polyurethane (TPU) possesses recyclable and eco-friendly characteristics, along with the elasticity of rubber and exceptional mechanical properties. In this study, a flexible and high-filtration performance PP-TPU textile material was developed by melt-blowing for filtering PM0.3 aerosols. For the first time, a melt-blown PP-TPU nonwoven was used as an air filter. The fiber morphological studies exhibited that addition of 10 and 20 wt.% TPU into PP resulted in a fiber diameter increment from 0.94 to 1.24 mu m. Also, melt-blown PP-TPU forms helical fibers, which are different from fibers noticed in melt-blown PP. Corona-charged double-layer 80PP-20TPU nonwovens have a filtration efficiency of 99.25% and quality factor (QF) of 0.13 mm H2O-1 at an air flow rate of 95 L/min. Moreover, PP's tensile strength was increased by 72.22%, and elongation was raised by 38.1% with the addition of 20 wt.% TPU. Thus, PP-TPU melt-blown composites may bring novel perspectives into the design and development of high-performance filtering materials for a variety of applications.Öğe Fabrication ofco-PVDF/modacrylic/SiO2nanofibrous membrane: Composite separator for safe and high performance lithium-ion batteries(Wiley, 2021) Al Rai, Adel; Stojanovska, Elena; Akgul, Yasin; Khan, Mohammad Mansoob; Kilic, Ali; Yilmaz, SafakHighly porous free-standing co-poly(vinylidene fluoride)/modacrylic/SiO(2)nanofibrous membrane was developed using electrically-assisted solution blow spinning method. The performance and the potential of the membrane as a lithium-ion battery separator were investigated. The addition of modacrylic enhanced the solution spinnability that resulted in defect-free membranes. Moreover, the presence of modacrylic enhanced the dimensional and thermal stabilities, while the addition of hydrophilic SiO2 nanoparticle enhanced both mechanical property and ionic conductivity. Combustion test results illustrated that the presence of modacrylic provide flame retarding property over a set of different polymeric-based membranes. Electrochemical performance results showed that the developed membrane can increase the battery capacity compared with the commercial separator.Öğe Hydrothermal carbon effect on iron matrix composites produced by powder metallurgy(Elsevier Science Sa, 2020) Simsir, Hamza; Akgul, Yasin; Erden, Mehmet AkifIn this work, hydrothermal carbons (HTC) were obtained from glucose at 200 degrees C for 30 h. HTC and its calcinated product (HTC*) were added to pure iron powder with different ratios (0.25, 0.50 and 0.75 wt%) to obtained HTC reinforced iron composites by powder metallurgy. To our knowledge, this is the first study that investigates the effect of HTC on iron matrix composites. Microstructure, hardness, compression and corrosion behaviors of composites were investigated. According to the results, mechanical properties of composites were enhanced with the increasing of HTC/HTC* amount. However, high corrosion resistances were gained with the using of the low amount of HTC (0.25 and 0.50 wt%) and HTC* (0.25 wt%).Öğe Improved wear properties of magnesium matrix composite with the addition of fullerene using semi powder metallurgy(Taylor & Francis Inc, 2018) Turan, Muhammet Emre; Sun, Yavuz; Akgul, YasinThe present study aims to fabricate fullerene (C60) reinforced magnesium matrix composite via semi powder metallurgy in hot press system under high purity argon atmosphere. Improvement of wear resistance of pure magnesium with the addition of fullerene is also aimed with this study. Hardness and wear tests at room temperature were performed to investigate the mechanical effect of fullerene nanoparticles. Microstructures of fabricated composites were characterized using Scanning Electron Microscope (SEM). Results clearly show that hardness performance was improved up to 0.5wt. % fullerene addition directly. A uniform distribution was also achieved according to the mapping and line EDX analysis for the lower content of fullerene. Agglomeration of fullerene was observed for 1wt. % reinforced composite. Wear performances of pure magnesium were also improved when harder fullerene reinforcements incorporated into the matrix. Abrasion and oxidation were main wear mechanism for unreinforced and fullerene reinforced composites. Enhancement of hardness and wear performances might be attributed to the high specific surface area of fullerene and achievement of uniform distribution of reinforcement in magnesium matrix.Öğe Influence of carbon fiber content on bio-tribological performances of high-density polyethylene(Iop Publishing Ltd, 2019) Akgul, Yasin; Ahlatci, Hayrettin; Turan, Muhammet Emre; Erden, Mehmet Akif; Sun, Yavuz; Kilic, AliThe present study aims to investigate the effect of short carbon fiber (SCFs) content on wear performance of high-density polyethylene (HDPE). SCFs reinforced composites with different weight fractions (5 wt%, 10 wt%, 15 wt% and 20 wt%) were fabricated by melt compounding and compression molding. To evaluate bio- tribological performance of the samples, three different loads (20 N, 40 N and 60 N) were applied to simulate body fluid (SBF) environment against stainless steel counterface. The scanning electron microscope was used to investigate the morphology of composite granules and worn surfaces of samples. Also, the hardness test was conducted for all samples. The results show that the hardness of high-density polyethylene increases significantly depending on the short carbon fiber content. 20 wt% SCFs reinforced composite exhibited the highest hardness, which is 34% improvement compared to the pure HDPE. However, the same trend was not observed for wear resistance of composites. Composites containing 10 wt% SCFs showed best wear performance in SBF fluid conditions.Öğe Influence of multi-wall carbon nanotube content on dry and corrosive wear performances of pure magnesium(Sage Publications Ltd, 2018) Turan, Muhammet E.; Sun, Yavuz; Aydin, Fatih; Akgul, YasinThe present study aims to investigate the effect of Multi-Wall Carbon Nanotube on dry sliding and corrosive wear performance of pure magnesium. Multi-wall carbon nanotube reinforced composites with different weight fractions (0.25wt.% and 0.5wt.%) were fabricated by semi powder metallurgy. Hardness test was performed for all samples. To evaluate wear performance of the samples, three different loads (10 N, 20 N, and 40 N) were applied at the room temperature in both dry and 3.5wt.% NaCl corrosive environments. Worn surfaces and microstructures of the samples were characterized using Scanning Electron Microscope. Results show that carbon nanotubes embedded in the matrix without any macro-defects. The hardness of pure magnesium was improved with the addition of multi-wall carbon nanotube considerably. 0.5wt.% multi-wall carbon nanotube reinforced composite exhibited best wear performance both in dry and corrosive conditions.Öğe Investigation of the properties of Al7075-HTC composites produced by powder metallurgy(Sage Publications Ltd, 2021) Arsun, Ozan; Akgul, Yasin; Simsir, HamzaEven though aluminium matrix composites have been used in many different application areas, the improvement of its mechanical, tribological, and corrosion properties is crucial for enlargement of its application areas. To achieve this, many ceramic-based and carbon-based additives have been used. However, eco-friendly and low production cost hydrothermal carbons (HTCs) have not been used, yet. In this study, three different amounts of HTCs (0.25, 0.50, and 1.00 wt.%) produced from cellulose were used as a reinforcement material in Al 7075 by powder metallurgy for the first time. According to the mechanical, tribological, and corrosion test results, all of the mentioned properties of Al 7075 alloy were improved by reinforcing with HTCs. As a consequence of this study, HTCs can be used as appropriate reinforcement materials for the aluminium matrix composites.Öğe Mechanical and dynamic mechanical thermal properties of ensete fiber/woven glass fiber fabric hybrid composites(Elsevier Sci Ltd, 2021) Negawo, Tolera A.; Polat, Yusuf; Akgul, Yasin; Kilic, Ali; Jawaid, M.This study aimed to identify the effects of the stacking sequences on mechanical and dynamic mechanical properties of ensete/glass hybrid composites. The composites were fabricated by using 4 layers of carded ensete web and woven glass fabric by Vacuum-assisted resin transfer molding method. Mechanical and dynamic mechanical properties of hybrid composites were characterized. The test results showed that hybridization of ensete web with glass woven fabrics enhanced the mechanical properties of ensete composites. The morphology of fractured samples reveals that higher glass fibers pullout than ensete fibers in hybrid composites. The flexural properties also increased when glass fiber hybridized with ensete fiber and the optimum values obtained when it is used as the skin of the composite.The composites stacked as glass-ensete-glass (GEEG) showed higher storage modulus as compared to glass-ensete (GGEE) ensete composites whereas loss modulus of the composites reinforced with glass fiber exhibited the maximum value of 407 MPa and the height of the damping curve decreased in GEEG composite. Experimental studies showed that the ensete/glass fiber hybrid polyester composites can be used as load-bearing structures and components where high resistance to deformations and thermal stability is necessary.Öğe MECHANICAL PROPERTIES OF GRAPHENE-NANOPARTICLE AND CARBON-NANOTUBE-REINFORCED PE-MATRIX NANOCOMPOSITES(Inst Za Kovinske Materiale I In Tehnologie, 2019) Erden, Mehmet Akif; Akgul, Yasin; Kayabas, Ozge; Ahlatci, Hayrettin; Cetinkaya, Kerim; Ozturk, Fatih HuzeyfeIn this study, graphene-nanoplatelet (GNP) and carbon-nanotube (CNT) reinforced nanocomposites were produced with pressure molding. 1 w/% of GNPs and 1 w/% of CNTs were separately added to a polyethylene (PE) matrix and 0.5 w/% of both reinforcements was also jointly added to the PE matrix. In this manner. the effects of GNPs and CNTs on the mechanical properties of PE were compared and the synergistic effect was investigated. In order to examine the mechanical properties, a tensile test, a hardness test and a wear test were applied to the produced samples. Also, fracture surfaces and wear surfaces were investigated with a scanning electron microscope (SEM). It was observed that the graphene was distributed homogeneously in the polyethylene matrix. Thus, the GNP-containing samples showed better mechanical properties than the CNT-containing samples.Öğe Mechanical, tribological and corrosion properties of fullerene reinforced magnesium matrix composites fabricated by semi powder metallurgy(Elsevier Science Sa, 2018) Turan, Muhammet Emre; Sun, Yavuz; Akgul, YasinIn this study, fullerene reinforced magnesium matrix composites were produced by semi powder metallurgy using ultrasonication, drying, hot pressing and sintering. Pure magnesium and 0.5 wt% fullerene reinforced composite were characterized for microstructure, mechanical, wear and corrosion properties. The experimental tests revealed that hardness behavior of pure magnesium was improved considerably with the addition of fullerene. Microstructural observations exhibited that fullerene nanoparticle is homogenously embedded in magnesium matrix. According to the compression test results, compression yield and ultimate strength were improved significantly. Furthermore, fullerene reinforced composite showed lower wear rate and coefficient of friction than unreinforced magnesium. However, corrosion rate was increased when fullerene incorporated into the matrix. (C) 2018 Elsevier B.V. All rights reserved.Öğe Mechanical, tribological, and biological properties of carbon fiber/hydroxyapatite reinforced hybrid composites(Wiley, 2020) Akgul, Yasin; Ahlatci, Hayrettin; Turan, Muhammet E.; Simsir, Hamza; Erden, Mehmet A.; Sun, Yavuz; Kilic, AliThe present study aims to investigate the effect of short carbon fiber (SCFs) and hydroxyapatite (HAp) content on mechanical, tribological, and biological properties of high-density polyethylene (HDPE) matrix composites. The proposed HDPE/SCFs-HAp hybrid composites with good mechanical-tribological behavior and biocompatibility might be used as novel implants in orthopedics. The composites were developed using twin-screw extrusion and compression molding methods. Hardness, tensile, and 3-point bending tests were performed to investigate the mechanical properties of hybrid composites. To evaluate wear performance of the samples, three different loads (10, 20, and 30 N) were applied in simulated body fluid. Biological activities of the hybrid composite samples were investigated. Results show that HDPE-10%SCFs-10%HAp sample provides optimum mechanical, tribological, and biological properties.
