Yarn twist

It has been known for some time that the color of fabrics and the types of dyes used can be important factors in determining the solar reflectance of fabrics (15., l6). However, color of fabrics in apparel has no effect on the loss of body heat since the color of a fabric has a small effect on its surface emittance (16). Other factors such as fiber orientation and length, yarn twist, and fabric structure also influence the infrared and visible reflection properties of various fabrics (17). In a recent study, the various radiant properties of textiles measured at the peak emission wavelength of sunlight (0.6 urn), were found to approach constant values of absorptivity (0.67), absorptance (0.33), transmissivity (0.0), and reflectivity (0.33) at infinite superficial density (3.) ... 

The form in which the materials are exposed is also relevant (27). The inner parts of a coarse yarn or heavy fabric may be relatively undamaged while the outside is degraded thus, the strength retention of such samples may be higher than that of a finer yam or lighter fabric. Yarn twist can also have an effect since low-twist yarns are damaged a little more rapidly than higher-twist samples (28). 

Inspection of the fabric attribute dimensions for all location points revealed that certain attributes were either absent or unrecognizable. These attributes are fiber bundle, fiber single, fiber crimp, fiber surface, fiber pattern, yarn type, and yarn twist direction. Therefore, these attributes were deleted from the statistical analysis. The remaining attributes were either present at all location points or exhibited variation. These attributes included the three (layers, 1/1, and float) whose interactive effects had direct relevance to the research hypothesis, and the following fiber and yarn attributes paired fibers, 0 twist, combined yarns, yarn system A, yarn systems A + B, yarn systems A + B + C + D, fabric distortion, red, green, and black. 

Fabric composites have mechanical properties similar to those of laminates made from orthogonal uni-directional layers. However, fibre curvature arising from yarn twist and weave crimp makes fabric reinforcement less efficient than in the case of aligned straight fibres. 

Gauze goz [MF gaze] (1561) n. A thin, sheer-woven fabric in which each filling yarn in encircled by two warp yarns twisted around each other, gauze is similar to... 

D. Zimliki, Modeling the Strength of Flat Yarns, Twisted Yarns, and Two-Ply Cords from Single Filament Data, M. S. Thesis, Department of Chemical Engineering, Clemson University, 1998. 

Polymer yarns twisted/embedded with metallic wires... 

Winders are used at the end of the spinning process, LSS or HSS, or at the end of an integrated process (spin-draw winding see Section 17.4.9), always at high speed. Winders for separate drawing processes (see Section 17.4.9) usually operate at <1000 m min f At these low speeds it is possible to wind and twist the yarn simultaneously. This is done for textile yarns. For industrial yarns twist is often applied as a separate aftertreatment. 

Elastic Properties of Twisted Yarn Biocomposites 339 Table 10.1 Tensile properties of unidirectional composites with various yarn twist angles. 

Fibers are normally spun into yarns with the exception of nonwovens (Chapter 6). A selection of typical yarn structures is shown in Fig. 1.11. The so-called spun yarns are yarns made from staple fibers (for example cotton and cut man-made fibers). All other yarns are made from man-made fibers. Plied yarns consist of two or more parallel oriented yarns twisted yarns consist of at least two twisted yarns. 

The fibers are twisted without stress between the pull-off nozzle and the rotor groove. The yarn twist is produced by the rotation of the rotor and the pull-off from the rotor and by a false twist at the pull-off nozzle. This false twist contributes significantly to the spinning stability and is removed again later (Eqs. 3.6-3.8). 

A technological characteristic of OE-rotor spinning is the presence of wrapper fibers (Fig. 3.19). When fibers are attached to the end of the twisted yarn in the rotor groove (a), they wind around the yarn end with one fiber end in the direction of yarn twist and with the other fiber end opposite to the direction of yarn twist (b-d). Such wrapper fibers, also called blurbs, are characteristic for OE-rotor yams. The resulting yarn appearance is attractive in some products, for example, blue Jeans. In other products, these wrapper fibers are unwanted. In yarns for cut-pile carpets, wrapper fibers are disadvantageous, as they prevent the pile from opening uniformly. 

Yarn twist P = z 10 -a m target false twist O n z Twist factor Machine efficiency (%) Number of spinning positions... 

Yarn twist target (1/m) n j yam W delivery Yarn draw-off speed... 

Yarn twist caused by rfwt Effective diameter of the draw-off jet... 

The yarn twist (number of turns per meter of yarn) is also an important property for yarns and especially for ply-yarn yarns. 

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