Stana Kovačević

Influence of Warp Loading on Weaving Machines upon Yarn Deformation

The breaking force of warp yarns taken per segments on the loom is measured using three weaves from the same warp on different looms. To simulate the deformation of warp yarns, samples from the warp beam are taken and, after various conditions of cyclic stress on a dynamometer, the most approximate degree of warp deformation is that which occurs in the weaving process per segments on the loom and per weave types. The F-test, t-test, χ2-test, and correlation coefficient reveal that there are no differences among breaking force values of the yarns from the looms or on yarns after cyclic stress and relaxation measured on the dynamometer, meaning that deformation imparted to the warp on the loom during weaving is very similar. Deformation caused by friction among yarns and imparted by metal pieces is not discussed here, but is included in the deformation caused by stress. Under the same conditions of cyclic stress, the elongation of the warp during stress in the segments of the loom is tested, and the conclusion is reached that elongation follows yarn deformation almost linearly. Investigations involve the same weaving conditions on the same loom and with the same warp, employing the three weaves. Dynamic tension of the warp is measured for each weave in the course of weaving, and the change in tension caused by changing the weave is registered.

Coated Textile Materials

Coated textile materials consisting of woven or knitted fabric as a basic component increasingly represent an indispensable product for a specific purpose. The artificial polymer material used for the purposes of this paper consists of the substrate and coating. Polyurethane polymers are mostly used for coating because they enable numerous applications, considerably more numerous than others. They can be used as furniture upholstery, as medical devices, in industry, as protective clothing against rain, wind etc., in household, sports etc. Coated textile materials as relatively new products are increasingly developed every day. Since new materials are constantly designed for specific purposes, they are often unknown in terms of quality. Thus, there is a necessity for intensive investigations in order to obtain a higher quality, more environmentally friendly and more suitable product.This chapter will deal with basic properties and advantages of coated materials consisting of a woven or knitted fabric as a basic component. The complexity of making structural coated materials and their design require a fundamental analysis. The selection of raw materials according to components, thickness of components according to layers and manufacturing method depends on the purpose of the final product. Due to the specific use of coated materials the materials used for furniture upholstering with a woven fabric as the basic component and for protective clothing with a knitted fabric as the basic component will be described.

The Effect of Microwave Drying on Warp Sizing

The paper describes our research of microwave usage in drying the size pick-up. An analysis of three different drying processes in relation to physical-mechanical properties of sized yarn has been carried out. Under the same sizing conditions, but different drying methods, the following parameters were determined: breaking force, elongation at break, abrasion resistance and yarn hairiness. The application of microwave drying method for warp sizing showed to be equally good, or even better in some cases, compared to the conduct and convection drying methods.

Analysis of changes in mechanical and deformation properties of yarn by sizing

The purpose of this paper is to show the degree of changes in mechanical and deformation properties of single cotton yarn after sizing depending on their fineness, size concentration and the structure created by the type of yarn spinning. The properties of ring and rotor-spun yarns were analyzed before and after sizing with a PVA sizing agent, using the same recipe, but with two different size concentrations — 7.5% and 5.0%. Standardized methods for determining the mechanical properties were used, as well as a modified method for cyclic testing to determine areas of elastic, viscoelastic and plastic yarn deformations. There are no significant differences in yarn properties after sizing with lower and higher size concentrations, which leads to the conclusion that it is a greater advantage to use a lower concentration, in order to achieve better economic and environmental effects. By sizing, a ring-spun yarn achieves major improvements, particularly in more refined yarns (20, 30 tex), which is positive because improvements in mechanical properties of these yarns are more necessary. Contrary to this, with a rotor-spun yarn the improvements are relatively low, due to its structure. Cyclic loading of yarn showed a difference in changes of deformation areas of unsized and sized yarns, primarily in the way of reducing the elastic area of deformation, depending on yarn structure. Information obtained by this analysis can improve the quality of sizing with possible cost savings and contribute to a better regulation of weaving conditions and thus to an increase in the quality and performance of weaving.

Analysis of Size Pick-up and Mechanical and Surface Properties of Multicolored Warps

The impact of various colors in a multi-colored warp on size pick-up was tested. Likewise, the change of physical-mechanical properties of yarn by sizing multi-colored warps was examined. Tests were performed on various multicolored warps for each color. Based on the obtained results, we concluded whether there was a difference in the size pick-up among various colors of the warp, as well as a difference in physical-mechanical yarn properties under the same sizing and dyeing conditions.

Analysis of the Mechanical Properties of Woven Fabrics from Glass and Basalt Yarns

Among many other materials for the reinforcement of composites, technical fabrics are increasingly being used for the same purpose, especially from glass and basalt tows, which have good mechanical properties.. During tensile stress these fabrics are elongated in the direction of tensile force, and at the same time they contract crosswise in relation to the action of the tensile force. In this paper the tensile properties of woven fabrics made from glass and basalt yarns were investigated. Measurements were focused on the lateral contraction, according to which Poisson’s ratio can be calculated. For these purposes, an innovative device as an upgrade of the strength tester and samples of fabrics of non-standard shapes (cross and square) were used. Mechanical properties of the yarns from which the fabrics were made were analysed before and after weaving in order to define the impact of weaving on them.

Weaving Complex Patterns — From Weaving Looms to Weaving Machines

A chronological overview of the historical facts of the art of hand weaving, with an emphasis on the development of large and complex patterns is provided. The development of looms or weaving machines through history for weaving fabric with large patterns is described. Hand weaving complex patterns from primitive weaving on frames to more complex weaving with two weavers operating one loom was especially explored. The beginning of Jacquard weaving and its application even to the electronic Jacquard looms has been emphasized. An analysis of the development of patterned fabrics with multiple effects was carried out. The nalysis was conducted according to patterns using the shortened version of drawing a sample. The results show that it is possible to determine the echnique of weaving and construction parameters of each fabric pattern that vary in color and/or in a weave used. The most accurate way to ighlight the contours of the points of the transition of one effect into another, namely by shifting warp and weft interlacing points on the edges of each pattern (opposing thread float), is described. Based on the obtained results and finding an identical yarn, it is possible to replicate the pattern on the Jacquard loom.

Physical–mechanical properties of automotive textile materials

The role of automotive textile materials is of great importance and therefore this paper analyses the properties of such materials – airbag fabrics and upholstery fabrics. Fundamental characteristics and construction parameters of airbag fabrics and artificial leather with bonded textile fabric on the back side, as well as joining (sewing) and quality of joining places of cut parts are crucial for durability, comfort and aesthetics of the automotive interior design, and therefore were analysed. Airbag fabric specificity and extreme values of several parameters are achieved by manufacturing process, with extremely high densities in the warp and weft direction, resulting in a great strength and air permeability properties of very low level. The most important parameters for upholstery fabrics (artificial leather) durability are breaking force and elongation at break, and they were tested in different circular directions. Tests showed the direction with greater breaking properties, what is of paramount importance.

Analysis of woven fabric at the place of the sewn seam

Abstract Key importance and the role of sewn seam in the woven fabric are presented. Fabric properties in the places joined with the sewn seam on which garment durability, applicability, appearance and quality depend are highlighted. Seam location is usually the weakest spot on the garment, especially when the great loads are present at these places. Mechanical properties of the sewn fabrics were investigated in different test conditions. The influence of the load on the sewn seam is analyzed in time intervals. Sample with seam have approximately 70% lower breaking properties (breaking force and elongation at break) than the sample without seam. By preloading the seam fabrics with 30%, 50% and 70% of elongation at break, for a 3-h period, the effect on mechanical properties were tested and the differences in pre-stretching intensity were observed. By conducting such test, it is expected that the fabric experience further degradation and that breaking properties further reduce, but the exact opposite occurred (breaking properties, by increasing the preload, increase even more), because of various material properties (structural fabric properties, raw material characteristics, seam characteristics).

Effects of Layer Thickness and Thermal Bonding on Car Seat Cover Development

In this work, composite materials for car seat covers composed of woven fabric + polyurethane foam (PU) + knitted fabric were tested by separation of components of the composite force, which are thermally connected with three different process speeds (30, 34 and 39 m/min) and two thickness PU (2 mm and 4 mm). The thermal bonding of the components into a composite is leading to reduction in thickness and weight of the composite compared to the amount of components before the joining. The force separation decreased as the speed for all samples increased. The smaller thickness of PU had an effect on the larger separation forces of composite components as well as higher abrasion damage. The purpose of this work was to investigate the influence of the thermal bonding speed of the composite components, the effect of PU thickness on the separation force, and abrasion properties.