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    Effects of dispersed and powdered silver nanoparticles on the mechanical, thermal, electrical and durability properties of cementitious composites
    (Elsevier Sci Ltd, 2019) Ceran, Ozge Bildi; Simsek, Baris; Doruk, Semahat; Uygunoglu, Tayfun; Şara, Osman Nuri
    This work aimed to analyze the thermal, electrical and mechanical properties of cementitious composites (CCs) modified with SNs in dispersed and powdered forms, using experimental design methods and image analysis techniques. It was concluded that SNs have smaller particle size increase thermal conductivity, ultrasonic pulse velocity and splitting tensile strength, and decrease electrical resistance, percentage of water absorption and porosity of CCs. It was found that the optimum usage level of powdered SNs in CCs is 2% by mass because of its tendency to agglomerate. However, it is more advantageous to use dispersed SNs when considering CC performance properties. (C) 2019 Elsevier Ltd. All rights reserved.
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    Nanomaterials Based Drinking Water Purification: Comparative Study with a Conventional Water Purification Process
    (Budapest Univ Technology Economics, 2019) Simsek, Baris; Sevgili, Inci; Ceran, Ozge Bildi; Korucu, Haluk; Şara, Osman Nuri
    One of the ways of fully securing the presence of fresh water is water treatment process. Nanomaterials and nanotechnology offers an innovative solution for water treatment. In this study, physical, chemical and microbiological improvement rates of raw water were analyzed after filtration with graphene oxide. Graphene oxide's water treatment performance; silver nanoparticles, silver nanoparticles & graphene oxide composites that are commonly used in water treatment were compared with a traditional treatment method. When compared to the traditional method, there were improvements of 50%, 40.7%, 86.8% and 45.5% for color, TIC, TOC and hardness properties, respectively in water treatment by GO-based filtration with solid liquid ratio of 0.7% (v/v). In water treatment with GO-Ag based filtration, 39.8%, 69.8%, 10.3% and 28.6% of improvements were obtained for TIC, TOC, hardness and LSI value compared to the conventional method. Both GO at 0.7% (v/v) solid-liquid ratio and GO-Ag nanocomposites were successful in the number of total viable microorganisms and inhibiting microorganisms such as Escherichia coil fecal (gaita-infected), Salmonella typhi, Enterococcus faecalis, Pseudomona aeruginosa and Staphylococcus aureus. Among the studied parameters GO-Ag nanocomposites found to be the most suitable for drinking water treatment.
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    Preparation and characterization novel dioctyl terephthalate blended polyvinyl alcohol-composite films incorporated with the graphene oxide and silver nanoparticles
    (Elsevier Sci Ltd, 2020) Ceran, Ozge Bildi; Simsek, Baris; Şara, Osman Nuri
    Dioctyl terephthalate is of great interest as a replacement for the phthalate plasticizers such as dioctyl phthalate and diisononyl phthalate due to its orthophthalate-free and non-carcinogenic properties. This study focused on the production, characterization and optimization of the quality characteristics of its film properties, such as the mechanical, hydrophilic and thermal properties of dioctyl terephthalate-blended polyvinyl alcohol composites modified with graphene oxide and silver nanoparticles using TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) based Taguchi Method. Dioctyl terephthalate has brought remarkable features, such as high elastic modulus, and hydrophilic and thermal stability to the polyvinyl alcohol matrix. The optimum Dioctyl terephthalate -blended polyvinyl alcohol films have a 2.26 times lower contact angle and a 13.41 times higher elastic modulus than the reference polyvinyl alcohol film. Dioctyl terephthalate should be preferentially used to manufacture more durable and hydrophilic composite films such as fibers, disposable underpad or industrial swab, instead of toxic phthalate plasticizers.
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    PVC concrete composites: comparative study with other polymer concrete in terms of mechanical, thermal and electrical properties
    (Springer, 2019) Ceran, Ozge Bildi; Simsek, Baris; Uygunoglu, Tayfun; Şara, Osman Nuri
    Recycling PVC wastes with conventional chemical recycling methods such as pyrolysis, gasification is not feasible due to the carbon dioxide and dioxin emmissions generated with these methods. PVC wastes can be disposed using in ready-mixed concrete which is the most commonly used building material. In this study, effects of waste PVC instead of fine aggregate and the effects of waste PVC on the concrete properties were analyzed using 0%, 30%, 35%, 40% and 45% (w/w) in the experiments. Effects of waste PVC in concrete were compared with the other waste polymer concrete in terms of mechanical, thermal and electrical properties. All waste polymers have reduced the mechanical strength of concrete as expected. Improvement rates for the splitting tensile strength for 28days are found to be 54.46%, 48.52% and 6.93% for PP, PET and rubberized concrete, respectively, in comparison with reference concrete. For thermal conductivity, improvement rates for 40% PC, 40% PP and 40% PVC concrete are found to be 52.56%, 44.87% and 42.31%, respectively. For electrical resistivity, the highest improvement rate was determined as 136.03%, 132.38% and 105.92% for PC, PVC and rubberized concrete, respectively.
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    Response Surface Methodology Based Desirability Function Approach To Investigate Optimal Mixture Ratio of Silver Nanoparticles Synthesis Process
    (Amer Chemical Soc, 2017) Karhan, Oznur; Ceran, Ozge Bildi; Şara, Osman Nuri; Simsek, Baris
    Silver nanoparticles are known especially because their antimicrobial properties can be used as conductive ink or adhesives for different electronics in compliance with their unique electronic and optical properties. As they are well-known, these practices require smaller nanoparticle formation. A response surface methodology based desirability function approach has been first applied to achieve the desired size of silver nanoparticles with the green synthesis methods. It is notable that the improvement rates at 7.9% by the mean of particle size distribution in AgNPs manufacturing process have been obtained with the utilization of utilizing the proposed methodology. When these results are evaluated, it can be seen that an 89.3% lower standard deviation has been obtained in comparison with the studies in literature. The results also show that the minimization of the nanosilver production variance should be performed to obtain the high quality and large scale manufacturing process.