Materials Engineering / Malzeme Mühendisliği
http://openacccess.atu.edu.tr:8080/xmlui/handle/123456789/506
2024-03-28T21:49:18ZInvestigation of Performance Properties of Denim Fabrics Containing Cotton/Sustans (R) Blend Rotor Yarn
http://openacccess.atu.edu.tr:8080/xmlui/handle/123456789/4186
Investigation of Performance Properties of Denim Fabrics Containing Cotton/Sustans (R) Blend Rotor Yarn
Ozkan, Muhittin; Baykal, Pinar Duru; Ozkan, Ilkan
It is common to use open-end rotor yarn in the production of denim fabric, which is preferred by people of all ages and social status due to its durability and comfort. Recently, the demand for stretch denim fabrics that can take the body's shape due to the elastic fibers in its structure has been increasing. However, producing elastane-containing yarns in the rotor spinning system is not as practical as ring spinning. For this reason, this study aimed to use the staple Sustans (R) fibers with high elasticity in the rotor spinning system together with cotton fibers and reflect the good elasticity and elongation properties of Sustans (R) fibers to the rotor yarns and denim fabrics. In the study, the staple Sustans (R) fibers based on PTT (Polytrimethylene Terephthalate) were spun with cotton fibers in the rotor spinning system. Then denim fabrics were produced using these yarns in the weft. Later, strength (breaking and tear), dimensional stability (dimensional change after washing, fabric elasticity and growth), abrasion resistance and pilling tests were applied to the produced denim fabrics. Thus, the effects of using Sustans (R) fibers on the strength, dimensional stability, abrasion and pilling properties of denim fabrics were analyzed. As a result of the study, the dimensional change and growth values after washing were developed by using Sustans (R). Although good dimensional stability was observed in the samples, the degree of elasticity was lower than expected. The use of Sustans (R) at rates of 50% and above improved the pilling values of the fabrics. In addition, it has been determined that the use of Sustans (R) in terms of abrasion resistance has a more positive effect at the end of long wear periods.
WOS indeksli yayınlar koleksiyonu. / WOS indexed publications collection.
TR Dizin indeksli yayınlar koleksiyonu. / TR Dizin indexed publications collection.
2022-09-01T00:00:00ZThe effect of powder preparation method on the artificial photosynthesis activities of neodymium doped titania powders
http://openacccess.atu.edu.tr:8080/xmlui/handle/123456789/4166
The effect of powder preparation method on the artificial photosynthesis activities of neodymium doped titania powders
Yurtsever, Husnu Arda; Ciftcioglu, Muhsin
The effects of nanostructure on the artificial photosynthesis activities of undoped and Nd doped titania (TiO2) powders prepared by three different chemical co-precipitation methods were investigated. Substitutional/interstitial N and S doping was observed in powders due to the presence of high concentrations of HNO3 (NP) and H2SO4 (SP) in the powder preparation media, respectively. Nd, N and S doping caused anatase/rutile phase transformation inhibition and crystallite size reduction in the nanostructure. Light absorption was significantly enhanced by Nd doping and the residual SO42-/NOx species in the nanostructure. Photocatalytic hydrogen production activity of Nd doped NP powder was 4 times greater than undoped NP powder at 700 degrees C and had a high purity (CO:H-2 ratio similar to 0.00). CO was determined to be the main product in photocatalytic CO2 reduction. NP powders had the highest CO yields and Nd doping enhanced CO production. The powders with high crystallite sizes and rutile weight fractions had the highest artificial photosynthesis activities.
WOS indeksli yayınlar koleksiyonu. / WOS indexed publications collection.
2018-11-01T00:00:00ZOptical properties of GaAs1-xBix/GaAs quantum well structures grown by molecular beam epitaxy on (100) and (311)B GaAs substrates
http://openacccess.atu.edu.tr:8080/xmlui/handle/123456789/4165
Optical properties of GaAs1-xBix/GaAs quantum well structures grown by molecular beam epitaxy on (100) and (311)B GaAs substrates
Gunes, Mustafa; Ukelge, Mulayim Ongun; Donmez, Omer; Erol, Ayse; Gumus, Cebrail; Alghamdi, Haifaa; Galeti, Helder Vinicius Avanço; Henini, Mohamed; Schmidbauer, Martin; Hilska, Joonas; Puustinen, Janne; Guina, Mircea
In this work, the electronic bandstructure of GaAs1-xBix/GaAs single quantum well (QW) samples grown by molecular beam epitaxy is investigated by photomodulated reflectance (PR) measurements as a function of Bi content (0.0065 <= x <= 0.0215) and substrate orientation. The Bi composition is determined via simulation of high-resolution x-ray diffraction measurement and is found to be maximized in the 2.15%Bi and 2.1%Bi samples grown on (100) and (311)B GaAs substrates. However, the simulations indicate that the Bi composition is not only limited in the GaAsBi QW layer but extends out of the GaAsBi QW towards the GaAs barrier and forms a GaAsBi epilayer. PR spectra are fitted with the third derivative function form (TDFF) to identify the optical transition energies. We analyze the TDFF results by considering strain-induced modification on the conduction band (CB) and splitting of the valence band (VB) due to its interaction with the localized Bi level and VB interaction. The PR measurements confirm the existence of a GaAsBi epilayer via observed optical transitions that belong to GaAsBi layers with various Bi compositions. It is found that both Bi composition and substrate orientation have strong effects on the PR signal. Comparison between TDFF and calculated optical transition energies provides a bandgap reduction of 92 meV/%Bi and 36 meV/%Bi and an interaction strength of the isolated Bi atoms with host GaAs valence band (C-BiM) of 1.7 eV and 0.9 eV for (100) and (311)B GaAs substrates, respectively.
WOS indeksli yayınlar koleksiyonu. / WOS indexed publications collection.
2018-12-01T00:00:00ZOne-pot synthesis of organic-inorganic hybrid polyhedral oligomeric silsesquioxane microparticles in a double-zone temperature controlled microfluidic reactor
http://openacccess.atu.edu.tr:8080/xmlui/handle/123456789/4155
One-pot synthesis of organic-inorganic hybrid polyhedral oligomeric silsesquioxane microparticles in a double-zone temperature controlled microfluidic reactor
Kibar, Gunes; Caliskan, Umutcan; Erdem, E. Yegan; Cetin, Barbaros
Polyhedral oligomeric silsesquioxane (POSS) particles are one of the smallest organosilica nano-cage structures with high multifunctionality that show both organic and inorganic properties. Until now poly(POSS) structures have been synthesized from beginning with a methacryl-POSS monomer in free-radical mechanism with batch-wise methods that use sacrificial templates or additional multisteps. This study introduces a novel one-pot synthesis inside a continuous flow, double temperature zone microfluidic reactor where the methodology is based on dispersion polymerization. As a result, spherical monodisperse POSS microparticles were obtained and characterized to determine their morphology, surface chemical structure, and thermal behavior by SEM, FTIR, and TGA, respectively. These results were also compared and reported with the outcomes of batch-wise synthesis.
WOS indeksli yayınlar koleksiyonu. / WOS indexed publications collection.
2019-07-01T00:00:00Z