Person: YÜKSEK, METİN
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YÜKSEK
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METİN
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Publication Metadata only The Effects of Fabric and Conductive Wire Properties on Electromagnetic Shielding Effectiveness and Surface Resistivity of Interlock Knitted Fabrics(KOREAN FIBER SOC, 2018) SANCAK, ERHAN; Sancak, E.; Akalin, M.; Usta, I.; Yuksek, M.; Ozen, M. S.Our aim in this study was to investigate the effects of course density, yarn linear density and thickness and type of conductive wire on electromagnetic shielding effectiveness. Metal/cotton conductive composite yarns were produced by the core-spun technique on the ring spinning machine, involving stainless steel, copper and silver coated copper wires with 40 mu m, 50 mu m, 60 mu m thicknesses and Ne10/1 and Ne20/1 count yarns. The interlock fabrics were knitted on a 7G flat knitting machine with the three different machine settings. The EMSE and the surface resistivity of knitted fabrics were measured by the co-axial transmission line method according to the ASTM-D4935-10 standard in the frequency range from 15 to 3000 MHz and by the ASTM D257-07 standard, respectively. It was observed that all fabrics shielded around 95 % of electromagnetic waves at low frequencies, 80 % at medium frequencies and 70 % at high frequencies. Increasing the course density and thickness of conductive wire in interlock knitted fabrics increased the EMSE correspondingly. The knitted fabrics that had been produced with high yarn count showed greater EMSE because there was less isolation. The effect of the metal wire type was highly significant between 15 and 600 MHz.Publication Metadata only Fibroin nanofibers production by electrospinning method(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2021) YÜKSEK, METİN; Saltik Cirkin, Derya; Yuksek, MetinSilk fibroin, which has many characteristic properties such as low inflammation reaction, biodegradation, suppleness, good antithrombogenic details, biocompatibility and high tensile strength is a very good candidate for biomedical applications. Electrospinning procures high surface area, porous, nanofiber dimension fiber generation, which is a plain method. An experimental study was carried out to produce nanofiber structure from silk fibroin by electrospinning and the electrospinning parameters for the spinning of uniform, continuous and silk fibroin fibers were optimized. As a result, the effect of variables of concentration, distance and applied voltage on the strength, thickness, surface structure, fiber diameter of nanomaterial was investigated. Then, in vitro cell viability of the silk fibroin mat was analyzed. It was seen that the strength, mat thickness, and fiber diameter increased with solution concentration rise. It was found that the values of the fiber diameter and tensile strength decreased with increasing distance. It was determined that the effect of distance varies depending on the concentration in the mat thicknesses. The tensile strength was affected inversely proportional the applied voltage rises and distance. It was found that the fiber diameter values decreased together with increasing applied voltage. At cell viability of silk fibroin mat was occurred high cell viability after 24 h, but it was obtained low cell viability at the 48th h.Publication Metadata only Development of bio-composite structures for Interior noise reduction in automobiles(2018-12-07) PARS, ABDULKADİR; SANCAK, ERHAN; BEYİT, ALİ; ÖZEN, MUSTAFA SABRİ; YÜKSEK, METİN; USTA, İSMAİL; PARS A., SANCAK E., BEYİT A., ÖZEN M. S. , YÜKSEK M., USTA İ.Publication Open Access Electromagnetic wave shielding and mechanical properties of vapor-grown carbon nanofiber/polyvinylidene fluoride composite fibers(SAGE PUBLICATIONS LTD, 2020-01) YÜKSEK, METİN; Yuksek, MetinThe demand for multifunctional requirements in aerospace, military, automobile, sports, and energy applications has encouraged the investigation of new conductive composite fibers. This study focuses on the development of Vapor-grown carbon nanofibers (VGCNFs) filled Polyvinylidene Fluoride (PVDF) composite fibers. Polyvinylidene fluoride (PVDF) reinforced with (1, 3, 5, and 8 wt.%) carbon nanofibers were produced as a masterbatch. The production of PVDF and PVDF/CNF composite fibers have been done successfully by using melt spinning processing technique. Conductive woven fabrics were produced with composite fibers on handloom machines to measure electromagnetic interference (EMI) shielding efficiency. Tensile strength of fibers increased with increase in CNF loading up to 3%. The tensile strength displayed a decrease of 5% and 8% CNF loading. Electromagnetic shielding effectiveness (EMSE) of woven fabrics with composite fibers were tested by using the coaxial transmission line method for planar materials standard that is based on ASTM D 4935-10. The electromagnetic shielding effectiveness of woven fabric which is consist of conductive composite fibers were increased with increasing CNFs loading and amount of fabric layers. It can be seen that the woven fabrics displayed between 2-10 dB and 2-4 dB EMSE values in the 15-600 MHz and 600-3000 MHz-frequency range, respectively. Nevertheless, it was observed that conductive filler content, dispersion, and network formation within the composite fibers were highly influent on the electromagnetic shielding effectiveness performance of the structures.Publication Metadata only Investigation of the Electromagnetic Shielding Effectiveness of Needle Punched Nonwoven Fabrics Produced from Stainless Steel and Carbon Fibres(INST CHEMICAL FIBRES, 2018) SANCAK, ERHAN; Ozen, Mustafa Sabri; Usta, Ismail; Yuksek, Metin; Sancak, Erhan; Soin, NavneetThe electromagnetic shielding effectiveness (EMSE) of needle punched, nonwoven fabrics produced using staple stainless steel and carbon fibres was investigated. Utilising carding and large scale industrial type needle punching machines, webs of staple stainless steel and carbon fibres were produced, which were subsequently bonded on the needle punching machine at approximately 132 punches/cm(2) and 13.5 mm needle penetration depth. The effect of varying the carbon fibre content was studied by varying the blend ratio of stainless steel and carbon fibres between 5-20%. EMSE measurements of as-produced needle punched nonwoven fabrics were carried out using the coaxial transmission line method (ASTM D4935-10) in the frequency range of 15-3000 MHz. Within the range, the EMSE values were enhanced from 22.3 dB (95/5, stainless steel/carbon) to 44.7 dB (80/20, stainless steel/carbon), which was attributed to the enhanced conductivity of the fabrics. In fact, the surface resistivity of the samples decreased from 5.80E + 3 Omega to 2.43E + 2 Omega, enhanced for 95: 5 and 80: 20 stainless steel/carbon blends.Publication Metadata only Morphological and mechanical analysis of electrospun shape memory polymer fibers(ELSEVIER SCIENCE BV, 2016) İŞGÖREN, ERKAN; Budun, Sinem; Isgoren, Erkan; Erdem, Ramazan; Yuksek, MetinShape memory block co-polymer Polyurethane (PU) fibers were fabricated by electrospinning technique. Four different solution concentrations (5 wt.%, 10 wt.%, 15 wt.% and 20 wt.%) were prepared by using Tetrahydrofuran (THF)/N,N-dimethylformamide (DMF) (50:50, v/v) as solvents, and three different voltages (30 kV, 35 kV and 38.9 kV) were determined for the electrospinning process. Solution properties were explored in terms of viscosity and electrical conductivity. It was observed that as the polymer concentration increased in the solution, the conductivity declined. Morphological characteristics of the obtained fibers were analyzed through Scanning Electron Microscopy (SEM) measurements. Findings indicated that fiber morphology varied especially with polymer concentration and applied voltage. Obtained fiber diameter ranged from 112 +/- 34 nm to 2046 +/- 654 nm, respectively. DSC analysis presented that chain orientation of the polymer increased after electrospinning process. Shape fixity and shape recovery calculations were realized. The best shape fixity value (92 +/- 4%) was obtained for Y10K30 and the highest shape recovery measurement (130 +/- 4%) was belonged to Y15K39. Mechanical properties of the electrospun webs were also investigated in both machine and transverse directions. Tensile and elongation values were also affected from fiber diameter distribution and morphological characteristics of the electrospun webs. (C) 2015 Elsevier B.V. All rights reserved.Publication Metadata only Characterization, mechanical, and antibacterial properties of nanofibers derived from olive leaf, fumitory, and terebinth extracts(SCIENTIFIC TECHNICAL RESEARCH COUNCIL TURKEY-TUBITAK, 2020) YÜKSEK, METİN; Sunter Eroglu, Nilsen; Canoglu, Suat; Yuksek, MetinIn this study, nanofiber structures were obtained with convenient polymers (PVA [polyvinyl alcohol] and PCL [poly Omega-caprolactone]) derived from the herbal extracts of olive leaves, fumitory, and terebinth plants. Optimum nanofiber structures were identified by measuring viscosity and conductivity values and performing morphological analysis, characterization, and mechanical tests of the prepared solutions. The potential use for wound healing at the most efficient level was determined as a result of antibacterial analysis of the structures obtained. APT (PVA/terebinth) and BFO (PCL/fumitory) nanofibers had the thinnest diameter range and the highest strength values. In terms of the determination of antibacterial effects, nanofiber structures of all 3 plant species proved to be effective against bacteria. The greatest effect was observed against Escherichia coli in the nanofiber structure containing olive leaves, with a zone diameter of 32 mm In addition, APT and BFO nanofibers had the highest values of thinness and strength. In these 2 samples, using BFO against Staphylococcus aureus and APT against Candida albicans increased their areas of activity. In the literature review, no study was available about obtaining nanofibers, especially from fumitory and terebinth plants. This study aimed to increase knowledge on obtaining nanofiber structures, including various polymers derived from olive leaves, fumitory, and terebinth plants.Publication Metadata only Electrospinning of single and multilayered scaffolds for tissue engineering applications(TAYLOR & FRANCIS LTD, 2017) BEYİT, ALİ; Erdem, Ramazan; Yuksek, Metin; Sancak, Erhan; Atak, Onur; Erginer, Merve; Kabasakal, Levent; Beyit, AliOptimized electrospinning conditions were applied to produce single and multilayered (ML) scaffolds composed of polycaprolactone, collagen and elastin. The ML scaffold was cross-linked with glutaraldehyde to increase the stability. Morphological and structural characteristics of the scaffolds were measured by SEM and FTIR analyses. Results revealed that polymers combined to each other well and uniform fibers were obtained with the diameters ranging from 156 +/- 53 to 1536 +/- 293 nm. Contact angle measurements were performed to investigate the hydrophilic character of each structure. It was observed that incorporation of the natural polymers into the blends increased the hydrophilicity. Mechanical tests proved that collagen contributed to fabricate stiffer structures while elastin provided more elasticity. Biocompatibility of the scaffolds was examined by SEM analysis and WST-1 test with mouse fibroblast cells (L929) in vitro. Results exhibited that the addition of natural polymers increased the cell growth, and none of the single and ML scaffolds presented cytotoxic effect.Publication Open Access Polyvinyl alcohol (pva) / cellulose acetate (ca) based environmentally friendly hybrid filter production(2022-10-20) ERTEK, DİCLE AYÇA; YÜKSEK, METİN; Ertek D. A. , Yüksek M.Abstract: In this study, the development of filters made of spunbond fabric coated with nanofiber surface was studied. With Covid 19, filters have gained importance in terms of human health. In this study, it is aimed to produce filters by using cellulose acetate and polyvinyl alcohol materials with the help of solution blowing method. The purpose of choosing polyvinyl alcohol (PVA) raw material is that it is not toxic and not polluting the environment, has high chemical stability, high abrasion resistance and low cost. Cellulose acetate (CA) material was chosen because it is a renewable, biodegradable, low-cost and high-quality fiber source that can be used in many manufacturing processes. These two materials were chosen in order to make the produced filter environmentally friendly and biodegradable. For the samples produced; tensile strength and FT-IR tests were carried out.Publication Metadata only The impact of solvent type and mixing ratios of solvents on the properties of polyurethane based electrospun nanofibers(ELSEVIER SCIENCE BV, 2015) PARS, ABDULKADİR; Erdem, R.; Usta, I.; Akalin, M.; Atak, O.; Yuksek, M.; Pars, A.Electrospun Polyurethane based nanofibrous membranes were fabricated from the solutions prepared with various volume ratios of N,N-dimethylformamide (DMF) and Tetrahydrofuran (THF). Properties of the blended solutions were analyzed in terms of viscosity and conductivity. The morphology of nanofibrous membranes were observed by SEM analysis. Experimental results revealed that the morphologies of polyurethane nanofiber membranes have been changed significantly with the solvent selection and mixing ratios of the solvents for the electrospinning. Diameter of the nanofibers was recorded in the range between 277 nm and 556 nm, respectively. Tensile strength and elongation measurements confirmed that mechanical characteristics of the nanofibrous membranes were strongly influenced by the fiber morphology and the uniformity. (C) 2014 Elsevier B.V. All rights reserved.