The effect of spinning parameters on friction spun core yarns tensile properties [Utjecaj parametara predenja na vlacna svojstva prede s jezgrom izradene frikcijskim predenjem]

Polyester staple fiber core/polyester staple fiber sheath and polyester staple fiber core/viscose staple fiber sheath DREF-3 core yarns are produced using different spinning parameters in order to explain the impact of these parameters on DREF-3 yarn tensile properties. Core yarns of 65 tex linear density are produced using three different core/sheath ratio levels, four different spinning drum speeds, three different air suction pressures at 4200 rpm constant opening roller speed and 100 m/min constant production speed. Tensile properties of the yarns are tested and the obtained results are evaluated using regression analysis with the SPSS statistical program at 0.05 significance level. Higher core/sheath ratio reduces both yarn tenacity and elongation ratio. The increase of spinning drum speed lowers core yarn tenacity; however, it does not have a significant effect on the elongation ratio. At higher air suction pressure, the PES/viscose yarn tenacity and elongation ratio rise. On the other hand, it has no significant impact on the tensile properties of PES/PES yarns

The influence of spinning parameters on polyester/viscose dref-3 yarn unevenness, imperfection and hairiness properties

In this study polyester staple fiber core/viscose sheath yarns were produced in order to understand the influence of spinning parameters on DREF-3 yarn unevenness, imperfection and hairiness properties. Yarns having 65 tex linear density, were produced with using three different core/sheath ratio level × three different spinning drum speed × three different air suction pressure at 4200 rpm constant opening roller speed and 100 m/min constant production speed. The unevenness, imperfection and hairiness properties of experimental yarns were tested with Uster Tester 3, at a speed of 200 m/min for 5 minute. Obtained results were evaluated with regression analysis using SPSS statistical pocket program at 0.05 significance level. According to analysis results, the air suction pressure is a significant factor for yarn hairiness. The increase of air suction pressure decreases the slippage between spinning drum cylinders and fibers (2). For this reason, at higher air suction pressure, the sheath fibers wrap better around core and yarn hairiness decreases. The wrapper fibers cause hairiness, due to their buckling form in the yarn. With the increase of sheath ratio, the number of wrapper fibers increase thus yarn hairiness increases. At higher spinning drum speeds the fibers in the sheath are damaged and the number of hooks at the end of fiber increases (2). As a result of this, yarn hairiness increases. On the other hand, the core/sheath ratio, spinning drum speed and air suction pressure are not significant factors for unevenness, the number of thin places, thick places and neps properties of polyester staple fiber core/viscose sheath yarns

Development of 3D hollow woven fabrics with superior mechanical properties by using nitinol and steel wire core hybrid yarns

In this study, nitinol and steel wire core hybrid yarns were produced from wires having two different diameters and used as warp yarns to weave 3D woven fabrics in two different fabric constructions. The steel bars with two different diameters were placed into the gaps between fabric layers to create a hollow form after fabric production. The fabrics produced with cold-worked nitinol wire were exposed to heat treatments at high temperatures to provide them shape memory property according to data obtained from DSC analysis. Conventional textile fibers are not durable to these temperatures; for this reason, carbon fiber was used both as sheath material of hybrid yarns and additionally as warp and weft carbon fiber yarns. All yarn and fabric tests were carried out simultaneously to evaluate the mechanical properties of nitinol and steel wire core hybrid yarns, and wire-reinforced fabrics. Tensile tests were applied to all wire and hybrid yarn samples, DSC and DMA analyses were conducted for only heat-treated nitinol wires. Low-velocity impact, tensile and pull-out tests were applied to fabric samples. Reference fabrics with no wire were produced and evaluated by comparing with wire-reinforced samples to provide a point of comparison to the data from the mechanical properties of wire-reinforced 3D fabrics. The study's results were analyzed with regression analysis using the backward method, and the parameters such as wire type, wire diameter, and fabric gap width for optimum fabric production were determined. Data obtained from all mechanical tests demonstrate that fabric samples with steel wire, thinner wire, and narrow gaps have better results than others. The effect of wire thickness was also found the same for the nitinol wire. DMA analyses show that the thinner nitinol wire is better than, the thicker one. Finally, an innovative technique has been developed in this study to weave carbon fiber on a conventional automatic sample loom without fiber breakage by twisting PVA yarn around the wire core hybrid and twisted carbon fiber yarns. © The Author(s) 2020.217M173The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was financially supported by TUBITAK 217M173 project

Adsorption of strontium from acidic waste solution by Mn-Zr mixed hydrous oxide prepared by co-precipitation

A manganese-zirconium mixed hydrous oxide with Mn to Zr mole ratio of 1:1 was prepared to study the sorption behavior and the removal of strontium from acidic radioactive waste solutions. Mixed hydrous oxide was identified and characterized by DTA/TGA, XRD, and surface analysis. The parameters affecting strontium adsorption, such as initial pH, contact time, initial metal ion concentration, temperature, adsorbent dose, and selectivity towards competing ions were investigated. Sorption data have been interpreted in terms of Freundlich and Langmuir equations. Thermodynamic parameters such as standard enthalpy (?H°), entropy (?S°), and free energy (?G°) were calculated from the slope and intercept of the plots of ln KD versus 1/T. The results indicated that the sorption of strontium onto manganese-zirconium mixed oxide is endothermic and spontaneous in nature. © Taylor & Francis Group, LLC.2006 NBE 008The authors are grateful to Ege University Research Foundation for providing financial assistance for this project under Research Contact No. 2006 NBE 008. -