Bülent Eker

Carbon nanotube-based nanocomposites and their applications

Abstract The purpose of the current review article is to present a compherensive understanding regarding pros and cons of carbon nanotube–related nanocomposites and to find ways in order to improve the performance of nanocomposites with new designs. Nanomaterials including carbon nanotubes (CNTs) are employed in industrial applications such as supercapacitors, and biosensors, and etc. The present article has been prepared in three main categories. In the first part, carbon nanotube types have been presented, as single-walled carbon nanotubes, multi-walled carbon nanotubes, and also equivalent circuit models, which have been used to more clarify the experimental measurements of impedance. In the second part, nanocomposites with many carbon, inorganic and polymeric materials such as polymer/CNT, activated carbon/CNT, metal oxide/CNT, and carbon fiber/CNT have been investigated in more detail. In the third part, the focus in on the industrial applications of CNTs. including supercapacitors, biosensors, radar absorbing materials, solar cells, and corrosion protection studies. This review article explains the latest advances in carbon nanotubes and their applications in electrochemical, electrical and optical properties of nanocomposites.

Design of a Wind Turbine Working with the Continuity Principal

In the study, the purpose is to take advantage of low wind potentials and obtain high power values with small rotor diameters. Wind speed is considered to be increased with the help of continuity principle. With this aim, two different wind tunnel inlet diameters were used, being 5 m and 10 m, while the outled diameters of wind tunnels were chosen as 0,5 – 1 – 2 – 3 – 4 m. The most striking result obtained in this study was the formation of a power of 492352 kW at the outlet of wind tunnel when the inlet diameter of wind tunnel was 10 m, outlet diameter was 0,5 m and the inlet wind speed was 4 m/s. Under these conditions, the wind speed at the wind tunnel outlet reaches 1600 m/s. A new viewpoint to wind energy technology will be presented if the results obtained in this study are also obtained in empirical studies.

Chapter 3.5 – Microstructure and Oxidation Behavior of Atmospheric Plasma-Sprayed Thermal Barrier Coatings

Abstract Thermal barrier coatings (TBCs) are widely used as insulation layered at elevated temperatures in gas turbine components. Yttria-stabilized zirconia (YSZ) ceramic has outstanding properties such as phase stability at high temperature, a prolonged service lifetime, and low thermal conductivity, which make it a promising candidate. The high temperature of gas turbines leads to the transfer of oxygen from the top coat to the bond coat; therefore, oxidation occurs on the bond coat; it is called the thermally grown oxide layer and is mainly considered a failure mechanism of TBC systems. Gas turbine engines that have applications in energy production, transportation, and the defense industry depend on high-temperature TBCs for higher efficiency. During thermal cycling, mechanical forces can occur in turbine engines, oxidation, hot corrosion, the sintering of the top coat, and a thermal expansion coefficient mismatch between the metallic substrate and the ceramic top coat as a result of spallation or crack degradation. TBCs can be affected by coating materials, manufacturing processes, and their microstructure. Spallation of the ceramic top coat is a main problem for TBCs because it leads to oxidation, corrosion, and creeps in the TBC system. This chapter gives brief information about thermal barrier materials and the microstructure and oxidation behavior of TBCs.

Developing Flat Drip Irrigation Pipes Using Bioplastic Materials

This study analyzed the use of environmentally friendly, cornstarch based bioplastic raw materials instead of polyethylene based raw material to produce flat drip irrigation pipes, which is the most efficient agricultural irrigation system. Two groups of raw materials were used in the study, low density polyethylene (LDPE) material and cornstarch based biodegradablepoly beta hydroxybutyrate (PHB) raw material. Mixtures are obtained by adding 4 types of PHB raw materials at the ratio of 25%, 30%, 35% and 40% and 5% black masterbatch separately in the form of granules. Test samples were prepared from these mixtures using extrusion film production method. Mechanical tests, shrinking tests and thermal analysis were performed on test samples. Of the raw materials with bioplastic mixture, only the sample obtained from 65% LDPE + 30% PHB + 5% black masterbatch was consistent with the values of commercially available flat drip irrigation pipes with 0.14 mm wall thickness, 443.54 % strain at break, 0.967 g/cm 3 density and 123.36 °C melting point. Moreover, raw materials with bioplast additives obtained from the study are suitable for the use as an alternative material in the polyethylene applications used in the fields of agricultural and industry. KeywordsFlat Drip Irrigation Pipe; Bioplastic; Polyethylene; Extrusion

Developing Packaging by Using Smart Material which Helps to Realize Spoilage in Yoghurt

The important effect of yoghurt on peoples health caused increasing of many technological works and researches not only in our country but also all over the world.The environment in which yoghurt kept, may cause many sort of germs and contamination paths by the effects of some factors which are fairly similar to its own structure. These factors change the shelf-life of yoghurt and finally cause spoilage in yoghurt. In this context, it is known that the scientific works in this area which are aiming to minimize this spoilage effect, focus on the yogurt structure and packaging of yoghurt. The aim of this paper is to improve a smart polymer material which interacts with serum and changes color of the package by considering serum occurring within the shelf-life of yoghurt. PP based material will be used with the biological agencies like “kaoline” and “talc” and implemented mainly or superficial, the color change will be arised if the serums PH increases. In practice, everyone can see the color changes with the window which will be placed on the label and the window will include the cautions according to the color levels.