Person: YILDIZ, ZEHRA
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YILDIZ
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ZEHRA
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Publication Metadata only SOYBEAN OIL BASED UV-CURABLE COATING FORMULATIONS FOR IMPROVEMENT OF WASHING FASTNESS OF WATERPROOF COTTON FABRICS(2022-05-19) YILDIZ, ZEHRA; YILDIZ Z., ÖNEN H. A. , GÜNGÖR A.Publication Metadata only Thermal Comfort of Woolen Fabrics Depending on Physical Properties(TAYLOR & FRANCIS INC, 2016) ATMACA, MUSTAFA; Dal, Vedat; Atmaca, Mustafa; Yildiz, Zehra; Ceviz, Nuray Oz; Hes, LubosIn this study, thermal comfort properties of woolen fabrics depending on the physical properties have been investigated. Thermal and water vapor resistance of fabrics have been measured by the PERMETEST instrument and air permeability has been investigated in a wind tunnel. The air permeability depends on the shape and value of the pores and inter thread channels, which are dependent on the structural parameters of the fabric. Theoretical model has been used in order to determine the porosity values. Experimental data and regression statistics proved that porosity and other fabric parameters have a very strong influence on thermal comfort property.Publication Metadata only A novel thermal-based fabric defect detection technique(TAYLOR & FRANCIS LTD, 2015) BULDU, ALİ; Yildiz, Kazim; Buldu, Ali; Demetgul, Mustafa; Yildiz, ZehraDuring the fabric production process, many defects can be occurred stemming from the unevenness in spinning, weaving, finishing processes, or from the raw materials. The fabric quality control process for the detection of these defects is carried out by specialist operators. In this paper, a new method based on the use of thermal camera for detecting these defects from the textile fabric images is presented. For identification process of defective area, fabric images were obtained by a thermal camera during the fabric flow in quality control machine that was specially designed for this experiment. Defective and defect-free regions on fabric surface were determined by thermal camera due to the thermal differences. The mentioned thermal defect detection system will eliminate the worker usage for fabric quality control process, thus it will provide a cost-effective and competitive manufacturing.Publication Metadata only Ultrafine Carbon Fibers with Hollow-Porous Multilayered Structure for Supercapacitors(PERGAMON-ELSEVIER SCIENCE LTD, 2016) YILDIZ, ZEHRA; He, Tieshi; Su, Qunyan; Yildiz, Zehra; Cai, Kedi; Wang, YoujiangElectrospun fibers of mixed polyacrylonitrile/polyvinyl pyrrolidine (PAN/PVP) sheath and silicone oil core were obtained by coaxial electrospinning. PVP and silicone oil were then removed from the coaxial electrospun fibers via phase separation and carbonization processes, respectively, to make the hollowporous multilayered ultrafine carbon fibers. The relationship between the morphology and electrochemical performance of ultrafine carbon fibers was investigated. Results show that the supercapacitor based on electrode of hollow-porous multilayered ultrafine carbon fibers exhibits high conductivity, fast ion diffusion, high specific capacitance (231.6 F.g(-1)), high charging/discharging efficiency (99.7%), and low internal resistance (0.2 Omega) using tetraethylammonium tetrafluoroborate in acetonitrile as electrolyte. Additionally, this work also demonstrates a great potential in the preparation of carbon nano-materials with graphene-like multilayer structure. (C) 2016 Elsevier Ltd. All rights reserved.Publication Metadata only Electrical properties and electromagnetic shielding effectiveness of polyester yarns with polypyrrole deposition(SAGE PUBLICATIONS LTD, 2012) USTA, İSMAİL; Yildiz, Z.; Usta, I.; Gungor, A.Polypyrrole was deposited on polyester yarns by vapour phase polymerization technique. Ferric chloride was used as an initiator. In order to determine the effect of the initiator concentration on polymerization process, four different initiator concentrations (0.2, 0.4, 0.6 and 0.8 mol/l) were used. The effect of the initiator in terms of tensile properties, electrical resistivities and morphological properties of the yarns was investigated. The polypyrrole deposited polyester yarns were then weaved in a handloom to form fabric for the investigation of surface resistivity and electromagnetic shielding effectiveness. Scanning electron microscopy, energy dispersive spectroscopy and Fourier transform infrared analyses illustrated that polypyrrole has penetrated into the yarn structure and the highest polypyrrole deposition was obtained at the initiator concentration of 0.6 mol/l. Also, the highest electromagnetic shielding effectiveness value and the lowest surface resistivity were obtained at this concentration.Publication Metadata only Preimpregnated natural fiber preforms(Elsevier Science, Oxford/Amsterdam , 2023-06-01) YILDIZ, ZEHRA; ERYILMAZ, OĞUZ; Yildiz Z., Eryilmaz O.Publication Metadata only Preparation of flame retardant epoxyacrylate-based adhesive formulations for textile applications(TAYLOR & FRANCIS LTD, 2016) YILDIZ, ZEHRA; Yildiz, Zehra; Onen, Aysen; Gungor, AtillaIn this research, UV-curable acrylated epoxy-based oligomer adhesive formulations containing vinylphosphonic acid (VPA) were prepared to adhere cord fabrics onto the rubber surfaces. In order to enhance the peel strength between cord and rubber, an alkali treatment was applied onto the cord fabrics prior to the adhesive application process. Adhesive formulations and alkali-treated cords were characterized by Fourier transform infrared (FTIR) spectroscopy. By changing the VPA ratio in adhesive formulation, peel strength, flame retardancy, and thermal properties were evaluated. Results proved that the 10% VPA-included adhesive formulation provided highest char yield values supporting the flame retardancy property and the highest peel strength value of 50.8N/cm between the cord fabric and rubber surfaces.Publication Metadata only Effects of NCO/OH Ratio and Reactive Diluent Type on the Adhesion Strength of Polyurethane Methacrylates for Cord/Rubber Composites(TAYLOR & FRANCIS INC, 2018) YILDIZ, ZEHRA; Yildiz, Zehra; Onen, Hacer Aysen; Gungor, Atilla; Wang, Youjiang; Jacob, KarlA series of dual curable polyurethane methacrylate-based oligomers were synthesized by changing the NCO:OH ratio and then were included in adhesive formulations using trimethylolpropane trimethacrylate and tricyclodecane dimethanol diacrylate (TCDDA) as reactive diluents. The effects of NCO:OH ratio and reactive diluent type on the structural properties of UV-cured free films and adhesion properties between polyester cord/rubber surfaces were studied. The highest adhesion strength of the 103Ncm(-1) was obtained when the NCO:OH ratio was set as 4 and the TCDDA was used as a reactive diluent. [GRAPHICS] .Publication Metadata only Synthesis and characterization of UV-curable cellulose acetate butyrate-based oligomers and their cotton fabric coatings(SPRINGER, 2021) BOZTOPRAK, YALÇIN; Dehmen, Ozan Gazi; Onen, Hacer Aysen; Yildiz, Zehra; Gungor, Atilla; Boztoprak, YalcinIn order to improve the thermal stability and flexibility, cellulose acetate butyrate (CAB) was modified with toluene diisocyanate-hydroxyethyl methacrylate (TDI-HEMA) adduct in various molar ratios. The obtained oligomer was characterized by proton nuclear magnetic resonance (H-1 NMR) and Fourier transform infrared (FTIR) spectroscopies. Gloss, cross-hatch, contact angle, and Taber abrasion tests were all used to investigate the film forming performance of the modified CAB oligomers on glass plates. The UV-cured free films of the synthesized oligomers were examined in terms of the mechanical tests. By using the synthesized CAB oligomers, coating formulations were prepared and applied onto cotton fabrics in order to make the cotton fabrics more durable in outdoor environments. The existence of the coating layer on the fabric surfaces was investigated by scanning electron microscopy (SEM). The coated UV-cured fabrics were evaluated separately in terms of abrasion, thermal conductivity, and air and water vapor permeability properties. Results proved that the oligomer (50%-CAB) in which 50% of the hydroxyl groups of CAB were reacted with TDI-HEMA adduct showed the best mechanical properties with the highest tensile strength and modulus values. Considering the coated fabrics, the least deformation against abrasion, the highest air/water vapor permeability, and the best thermal conductivity were all recorded in 50%-CAB coated sample.Publication Metadata only Dual-curable PVB based adhesive formulations for cord/rubber composites: The influence of reactive diluents(ELSEVIER SCI LTD, 2017) YILDIZ, ZEHRA; Yildiz, Zehra; Onen, Hacer AysenIn this study, the effects of reactive diluent type on the adhesion strength of cord/rubber surfaces were investigated. For this purpose, a urethane acrylate oligomer was synthesized by the reaction of 2,4-toluene diisocyanate (TDI), 2-hydroxyethyl methacrylate (HEMA) and polyvinyl butyral (PVB) in the presence of di-n-butyltin dilaurate (T12) as catalyst. The structure of the oligomer was characterized by nuclear magnetic resonance (NMR) spectroscopy. Then the oligomer was included in adhesive formulations together with trimethylolpropane trimethacrylate (TMPTMA) and tricyclodecane dimethanol diacrylate (TCDDA) as reactive diluents and thermal and photo initiator respectively. Polyester/polyamide cord fabrics were dipped into the adhesive solution and cured by UV-light. Then coated fabrics were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Contact angle measurement was employed to investigate the wettability properties of the coated fabrics. Thermal curing between the coated fabric and rubber was performed under heat and pressure. The adhesion strength between the cord/rubber surfaces was determined by T-peel test. The highest adhesion strength of 100.4 N/cm with the lowest contact angle value of 70.2 were obtained in the sample containing TCDDA as reactive diluent, due to a higher functionality resulting in a greater crosslinking density.