Oğuz Demiryürek

Thermal comfort properties of Viloft/cotton and Viloft/polyester blended knitted fabrics

Viloft is a special regenerated cellulosic fiber with a flat cross-section and crenulated surface that maintains air gaps in the yarns that help to improve the thermal properties of the fabrics. This fiber is mainly used for underwear, socks and sportswear fabrics and blends of Viloft with polyester or cotton are commonly preferred in the market. In this study, thermal-related characteristics, such as the thermal conductivity, thermal diffusivity, thermal absorptivity, thermal resistance, moisture and air permeability, of Viloft/cotton and Viloft/polyester blended knitted fabrics were investigated. For this purpose, 100%–0%, 67%–33%, 50%–50%, 33%–67% and 0%–100% blends of Viloft/cotton and Viloft/polyester slivers were produced and spun as 19.7 tex on a ring spinning system. In addition, single-jersey and 1 × 1 rib fabrics were produced and the comfort properties of these fabrics were measured using the Alambeta, sweating guarded hotplate, Permetest and air permeability testing devices. A simplex lattice design for the blended fabric properties was also developed and statistical analyses were carried out. According to the results, Viloft-rich blends, in general, improved the thermal properties of the fabrics. However, the relative water vapor permeability of Viloft/polyester blended fabrics was found not to be significant and only small significances were present for cotton blended ones, statistically.

Analyses and statistical modeling of crimp extension stage of single and multiple yarn ends pull-out in textured polyester woven fabric

The aim of this study was to understand the crimp extension stage of yarn, being pulled out of fabric. Polyester woven fabrics were used to conduct the pull-out tests. Yarn pull-out crimp extension depends on sample dimensions, fabric density, fabric weave, crimp ratio and the number of pulled ends in the fabric. Results showed that multiple and single yarn pull-out crimp extensions of long samples were higher than those of short samples, and the multiple yarn pull-out crimp extension was higher than that of the single-yarn pull-out force, and the crimp extensions in fabrics were proportional to their crimp ratios. Satin fabric weave showed high weft directional single and multiple pull-out crimp extension compared to plain and ribs fabric weaves. The developed regression model may be helpful for the design of multifunctional fabrics in technical textile applications.

Tearing properties of upholstery flocked fabrics

We have studied the tearing strength of substrate woven fabric, substrate with adhesive, flocked fabric and washed flocked fabric on dry and wet conditions. The tensile strength of the rubbed flocked fabric and rubbed washed flocked fabrics in dry and wet conditions were also researched, and a statistical model was developed for the analysis of the tearing behavior of these fabric forms. Warp and weft tearing strengths of rubbed flocked fabric and rubbed washed flocked fabric in wet conditions were slightly higher than those in dry conditions. The reason was partly the high wet strength characteristic of cotton fiber and partly the lubrication effect of acrylic adhesive under wet conditions. Although the weft density of the substrate fabric was around half of its warp density, there was a small difference between warp and weft tearing strengths of dry and wet states of rubbed flocked fabric. This was attributed to the dense structure having less free space and less ultimate deformation potential and ultimately reducing the tearing strength. When the stroke number increased, the warp and weft tearing strengths of dry and wet states of rubbed flocked fabric generally decreased. It was also found that the stroke number of wet rubbed flocked fabric and rubbed washed flocked fabric was low in comparison with stroke number of dry rubbed flocked fabric and rubbed washed flocked fabric. The reason was that the wet acrylic adhesive had poor properties. The results from the regression model were compared with the measured values mainly by the mean absolute percent error parameter which enables us to conclude that the developed regression equations explain the tearing strength of flocked fabrics.

Analysis of the CIE whiteness and whiteness tint of optically whitened cellulosic fabrics

In this study, the CIE whiteness (CIE WI) and whiteness tint (Tw) of optically whitened woven or knitted cellulosic fabrics (cotton, viscose, modal and tencel) irradiated with xenon arc light was investigated. The fabrics were whitened with four concentrations of eight different commercial optical whitening agents and these fabrics were irradiated with xenon arc light under specific conditions between 0—100 hours at 10-hour intervals. The reflectance of the optical whitened fabrics was measured by using spectrophotometry, while CIE WI and the Tw values were calculated using computer software. The results were investigated by statistical methods using ANOVA and regression curves in which CIE WI of optically whitened cellulosic fabrics were found to decrease seriously depending on irradiation time and Tw was also affected by xenon arc light.

Analysis and tensile characterization of flocked fabric after rubbing

In this study, the tensile properties of flocked fabric after rubbing were studied. A statistical method was used to analyze the generated data. For this purpose, woven fabric was used as a substrate and an acrylic adhesive was applied on this substrate to hold the polyamide flock fibers forming flocked fabrics. A rubbing test was applied in dry and wet forms to the flocked fabrics before and after washing. The tensile properties of these rubbed flocked fabrics were determined. The regression models developed in this study explain the relationship between rubbing and the tensile strength of the flocked fabrics. The results from this experiment could be used in the development of flocked fabric as seat covers for the automotive industry. The warp tensile strength of a flocked fabric is generally higher than its weft tensile strength due to its higher substrate density in the warp direction. Also, the weft tensile elongation of a flocked fabric is generally higher than its warp tensile elongation due to its higher crimp ratio in the weft direction. When the stroke number increases, the warp and weft directional tensile strength and the elongation of a flocked fabric generally decrease. In addition, the stroke number of a flocked fabric before and after washing is low in its wet form compared to the dry form. The main reason is that the acrylic adhesive has poor wet properties. Results from the regression models were compared with the measured values. It was concluded that the method used in this study could be a viable and reliable tool.

Sound absorbing properties of roller blind curtain fabrics

Roller blind fabrics are preferred and commonly used in home and office. In general, these fabrics are produced by coating the acrylic blended material, which is known by their ultraviolet properties, onto polyester woven fabrics. In this study, in order to characterize the sound insulation properties of roller blind fabrics, coating resin having different ratios of acrylic are applied onto different polyester woven structures. Sound absorption properties of these fabrics (front and back sides) are measured through dual microphone impedance tube and investigated by statistical analyses. Regression curves are obtained and optimum fabric properties on sound absorbing property have been suggested. As a result, acrylic content in coating material, fabric type, and viol structures occurred by coating process on the woven fabric are found as effective parameters on sound absorption properties of these fabrics. Increasing acrylic content in the resin up to 40% increases the sound absorbing value but further increasing this ratio yields sound reflection from the structure, in general. Optimum sound absorption and reflection values are provided with 40% acrylic rate in coating mixture.

Viloft/Polyester Karışımlı Örme Kumaşların Patlama Mukavemeti ve Boncuklanma Özelliklerinin Araştırılması

Viloft elyafi modifiye viskon olarak bilinmekte olup ozellikle polyester gibi elyaflarla karisim halinde kullanildiginda iplik icerisinde hava bosluklari olusturdugu icin kumaslarin termal ozelliklerini iyilestirmeye yardimci olmaktadir. Viloft/polyester karisimli orme kumaslarin bazi mekanik ozelliklerini karakterize edebilmek icin yapilan bu calismada 0/100, 33/67, 50/50, 67/33 ve 100/0 yuzde karisim oranlarinda viloft/polyester seritler elde edilmis olup bu seritlerden Ne30/1 lineer yogunlugunda ring iplikler elde edilmistir. Bu ipliklerden suprem ve 1x1 ribana yapilarinda orme kumaslar uretilerek bu kumaslarin patlama mukavemeti ve boncuklanma ozellikleri incelenmistir. Karisimda viloft oraninin artmasiyla patlama mukavemetinin dustugu gorulurken boncuklanma icin viloft oraninin artmasinin anlamli bir etkisinin olmadigi gorulmustur. Ayrica 1x1 ribana kumaslarin suprem kumaslara gore boncuklanmaya daha dayanikli oldugu bulunmustur.

Effects of Sample Dimensions on Pull-Out Properties of Woven Fabric Structures

The aim of this study was to understand the effects of fabric sample dimensions on pull-out properties of fabric weaves. Polyester woven fabrics were used to conduct the pull-out tests. A yarn pull-out fixture was developed and data generated from this research. Yarn pull-out forces depend on sample dimensions, fabric density, fabric weave, and number of pulled ends in the fabric. Results showed that multiple and single yarn pull-out forces of long samples were higher than those of short samples, and the multiple yarn pull-out force was higher than that of the single yarn pull-out force, and dense fabric has high pull-out force. Plain fabric weave showed high single and multiple pull-out forces compared to ribs and satin fabric weaves. The regression model could be used in this study as a viable and reliable tool. This research could be valuable for development of multifunctional fabrics in technical textile applications.