Wyniki wyszukiwania - BazTech

1

Influence of Twist on Selected Properties of Multifilament Yarn

Mertová I., Moučková E., Neckář B., Vyšanská M.

Autex Research Journal

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2018

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Vol. 18, no. 2

110--120

EN

Owing to twisting of filament fiber bundle, the structure and consequently various parameters and properties of a fiber bundle are changed. The aim of the work is to verify the effect of multifilament yarn twist (or twist coefficient) on selected mechanical properties such as multifilament tenacity, breaking elongation, and coefficient of fiber stress utilization in the yarn. Furthermore, the influence of twist on structural parameters such as the angle of peripheral fibers, the packing density, and the substance cross-sectional area of fiber bundle is observed. Two multifilament yarns with different filament cross-section shape and material were used for the experiment. Experimentally obtained data was compared with the known model dependencies derived decades ago based on the helical model. It can be stated that multifilament yarn retraction can be predicted based on the angle of peripheral fibers using the Braschler’s model. The coefficient of fiber stress utilization in the multifilament yarn determined experimentally corresponds with a theoretical curve, constructed according to Gégauff and Neckář, in the area of Koechlin’s twist coefficient α > 54 ktex1/2 m−1. Results as well as possible causes of deviations of experimental data from the theoretical one are discussed in this work.

2

Analysis Possibilities of Controlled Transport of Moisture in Woven Fabrics

Sirková B., Moučková E.

Autex Research Journal

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2018

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Vol. 18, no. 4

385--391

EN

The article is focused on testing of selected properties of linear and planar textiles from modified cotton yarns. In this article, the influence of woven fabric construction on wettability and possibilities of detection of moisture in the woven fabric is analyzed. Improving the physiological and hygienic properties for woven fabrics can be achieved with a specially designed textile structure in combination with a permanent surface finish of sub-set of yarns. Inserting of hydrophilic and hydrophobic set of threads in the woven structure makes possible controlled water transport. Controlled transport of water ensures good clothing comfort. Using such woven fabric, accumulation of water on the skin does not occur during the process of thermoregulation of the human body. The properties and behavior of the designed fabric will be determined by surface finishing of the warp and weft yarns (sub-set of yarns), which are supporting elements of the fabric.

3

Properties Of Viscose Vortex Yarns Depending On Technological Parameters Of Spinning

Moučková E., Mertová I., Jirásková P., Krupincová G., Křemenáková D.

Autex Research Journal

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2015

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Vol. 15, no. 2

138--147

EN

This paper analyzes the relationship between technological parameters of spinning of 100% CV Vortex yarns of different counts and its selected geometrical parameters (a lead of helix of wrapping fibre ribbon, yarn diameter) as well as yarn properties. The number of twist of wrapping fibre layer is determined. The effect of the yarn delivery speed, hollow spindle diameter, and the main draft on the hairiness, mass irregularity, tenacity, elongation, resistance to abrasion and bending rigidity of Vortex yarn is observed. The yarn properties are compared with the properties of open-end rotor spun yarns. Slivers of the same spinning lot were used for the production of both kinds of yarn. The results showed that the delivery speed in combination with spindle diameter affects yarn diameter, hairiness and abrasion resistance. Mass irregularity and imperfections of yarn is mainly affected by the main draft of drafting unit. Technological parameters of spinning do not affect the level of bending rigidity of the Vortex yarn. Tested rotor spun yarns had a larger diameter, higher hairiness, lower tenacity and higher elongation, lower mass irregularity and number of imperfections, higher abrasion resistance and lower bending rigidity compared to tested Vortex spun yarns.

4

Mechanical Properties Of Traditional And Nanofibre Textiles

Ursíny P., Bílek M., Moučková E., Pokorná M., Tumajer P., Wiener J.

Autex Research Journal

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2015

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Vol. 15, no. 3

198--206

EN

This study deals with a comparison of mechanical properties of a conventional yarn and a textile from nanofibres. The conventional yarn represents the textile objects with high degree of orientation of fibres and the textile from nanofibres represents the textile objects with low degree of orientation of fibres. The theoretical section is concerned with the issue of internal structure of plied yarn and resulting differences in the orientation and straightening of fibres and in utilisation of deformation properties of fibres in comparison to the referred nano textile. The experimental section describes the manner of realisation of both static and dynamic tests of conventional yarn and strips of nanofibres. The results show differences in the mechanical properties of conventional yarn and textile strip from nanofibres under static and dynamic loading conditions. The processing technology of conventional yarn has been verified in the long term. But textiles from nanofibres are a relatively new material and mechanical properties of the detected differences point out possible problems with their behaviour during standard technological processes.

5

New possibility of objective evaluation of yarn appearance: part II

Moučková E., Jirásková P.

Autex Research Journal

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2013

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Vol. 13, no. 1

1--10

EN

In this article, the possibility of new objective evaluation of yarn appearance in area employing selected spatial statistical functions is presented. The yarns wound on the boards were used for the experiment. Appearance of standard yarn boards from the standard CSN 80 0704 and real yarn boards with faultless and faulty yarns were converted into grayscale images. Fluctuation in degrees of grayness was evaluated between square fields in the image using statistical function called the area variation curve. In addition, the method was applied to the simulated yarn board appearance generated by the Uster Tester apparatus. Behavior of area variation curves in dependence on the result of visual evaluation of yarn board appearance was discussed. The generated appearances from the Uster Tester device were also evaluated by other statistical function called semivariogram. It was found out that the area variation curve is not a suitable tool for evaluation of yarn board appearance. The semivariogram seems to be a more suitable tool. The paper extends the knowledge on the issue of objective evaluation of yarn appearance and directly follows the author’s work [1].

6

New possibility of objective evaluation of yarn appearance

Moučková E., Jirásková P.

Autex Research Journal

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2012

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Vol. 12, no. 1

7--13

EN

The possibility of new and objective evaluation of yarn appearance wound on the board is described. A statistical method which has previously been used for the evaluation of surface unevenness of flat textile - semivariograms is used. The yarn board appearance is converted into a grey-scale image and the fluctuation in degrees of greyness between square fields in the image is evaluated by semivariogram. This method was applied on standard yarn boards from the standard CSN 80 0704 in addition to real yarn boards. The results of semivariograms constructed from a simulated ideal appearance of yarn on the board are discussed with the aim of introducing an ideal case behaviour of semivariograms. The possibility of using this function for the objective evaluation of yarn board appearance is also discussed.

7

Influence of structure of the yarn on mechanical characteristics of yarns exposed to dynamic stress

Tumajer P., Ursíny P., Bílek M., Moučková E., Pokorna M.

Autex Research Journal

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2012

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Vol. 12, no. 2

44--49

EN

This paper is a direct follow-up of the paper [1] describing in detail the VibTex equipment, which facilitates testing of textiles in a wide range of frequencies of their extension, as well as the determination of corresponding dynamic modules and loss angles. This equipment has been employed for testing polyester yarns of concordant fineness manufactured on ring and rotor spinning frames. At the same time, the material concerned has been subjected to a standard strength test. Therefore, the results of experimental measuring published in this paper allow us to assess the effect of the chosen spinning technology upon the mechanical properties of polyester yarns both at their static and dynamic loading. The introductory section of the paper contains a theoretical analysis of the effect of the chosen manner of spinning upon the mechanical characteristics of yarns. The experimental section indicates the results of measurements at static and dynamic loading, and the final section of the paper confronts the obtained pieces of knowledge with theory. This paper is part of a larger group of publications concerned with the behaviour of various linear textiles when exposed to dynamic loading (see [1],[2], [4], [5], [6]).

8

Research Methods for the Dynamic Properties of Textiles

Tumajer P., Ursíny P., Bílek M., Moučková E.

Fibres & Textiles in Eastern Europe

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2011

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Vol. 19, no. 5 (88)

33--39

EN

This paper is concerned with a theoretical description of the dynamic properties of textiles and their experimental analysis. In the theoretical section of the paper, the dynamic properties of textiles are described based on rheological models. To describe their dynamic characteristics, the Laplace transformation has been employed. The experimental section of the paper describes special equipment - VibTex and the possibilities of its use in the experimental analysis of the dynamic properties of textiles. The experimental section includes a description of the manner of determining the dynamic properties of textiles based on the results of measurement.

PL

W artykule omówiono zależności dotyczące właściwości dynamicznych tekstyliów oraz opisano badania eksperymentalne. Zależności teoretyczne oparto na opracowanych modelach. Dla opisania właściwości dynamicznych zastosowano transformaty Laplacea. W części eksperymentalnej przedstawiono VidTex - specjalne urządzenie do badan dynamicznych oraz możliwości jego zastosowania. Artykuł zawiera opis sposobu uzyskiwania parametrów dynamicznych tekstyliów.

9

Use of the VibTex vibration system for testing textiles

Tumajer P., Ursíny P., Bílek M., Moučková E.

Autex Research Journal

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2011

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Vol. 11, no. 2

47--53

EN

Principal objective of this paper is a description of a special testing device (VibTex). This device allows testing of textile materials (threads, samples of fabrics, etc.) during cyclical stress at a high frequency. Control of the VibTex allows harmonic and non-harmonic elongation of the textile samples. Results of the tests with harmonic elongation can be used for calculations of the dynamic characteristics of textile samples. In the final part of the paper, values of the dynamic modulus and loss angles are determined at frequencies of 10 Hz and 100 Hz for various yarns.

10

New method for the evaluation of woven fabric unevenness

Jiraskova P., Moučková E.

Autex Research Journal

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2010

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Vol. 10, no. 2

49--54

EN

Unevenness of woven fabric results from irregularity of the yarn used as well as from the process of its manufacture(weaving). A periodical and non-periodical yarn irregularity shows itself in the flat textile by known effects - themoiré effect, cloudiness, and stripiness. It is possible to predict the appearance of flat textiles from measured values of yarn mass irregularity and their characteristic functions (a spectrogram, a variance-length curve). The evaluation of surface unevenness of woven fabrics is done not directly but by judging their appearance, most often subjectively. For evaluation of flat textile appearance, it is also possible to use a so-called area-variation curve. The curve can be constructed on the basis of analysis of a woven fabric image either by a special program, created by J. Militky (Technical University of Liberec) in the programming environment Matlab, or by means of image analysis. By these methods it is possible to evaluate an image of real flat textile as well as a simulated image from an apparatus for yarn irregularity measurement. The woven fabric image is in grey scale. The variation coefficient of greyness degrees expresses the unevenness of flat textiles. In the experiment both real woven fabric images and simulated appearances of woven fabric, obtained by means of the apparatus Uster Tester IV, are evaluated by the methods mentioned above. The acquired area-variation curves are compared with each other and compared with visual evaluation of the woven fabric image. It was found that area-variation curves show only marked unevenness of woven fabric.