Core yarns

Another approach to flame-resistant cotton containing fabrics involves the use of core spun yarns [368 372]. There are two components in these specialized yarns. One component is a central core usually made from a human-made polyester or nylon, or a nonflammable core like fiberglass. The other component is a cotton cover that is wound around the central core to form the core yarn. The core yarn is woven or knitted into an appropriate textile, then treated with a finish to make the flame-resistant cotton cover. When the core yarns are spun to restrict their synthetic content to 40% or less, the FR treatment of the cotton component... 

Cut-resistant gloves are fabricated from a cut-resistant composite yarn having a core yarn and a first wrapping yarn helically wrapped around the core yarn. The core is of 56-220 dtex glass fiber filament yarn. The first wrapping is a 110-680 dtex para-aramid yarn. An additional yarn is made from aliphatic polyamides or polyesters. Further, the lining yarn is a composite yarn of 110-560 dtex of an elastomer [97]. 

Core-spun yarn n. A yarn made by twisting fibers around a filament or a previously spun yarn, thus concealing the core. Core yarns are used in sewing thread, blankets, and socks and also to obtain novelty effects in fabrics. 

Staple form for spirming with other fibers. A core yarn with a metal surface is produced by twisting a strip of metal around yarn of natural or manufactured fibers. The most important characteristic of me-talhc fiber and the chief reason for its use in textiles is glitter. Metalhc fibers are used as a decorative accent in fabrics for apparel, bedspreads, towels, draperies, and upholstery. A relatively new application for metalhc fibers is in carpet pile, where they are being used in small percentages for control of static electricity. 

Figure 10.19 Braid architecture (a) Localization of the braiding yarn, middle-end yarn, and core yarn for one pitch length, (b) The fiber path for one braid plait is represented by a cosine.

Fig. 4.3 (A) Schematic of conductive metal fiber twisted with the natural or synthetic fibers. From Swiss Shield. (B) Twisted metal wire The metal wire is twisted around the polymer yam. (C) Metal fibers The conductive yam consists of metal multtfilament. (B) and (C) from Lxicher, I., 2006. Technologies for System-on-TextUe Integration. Available at http //e-collection.library. ethz.ch/view/eth 28457 (accessed 20.01.14). (D) Conductive winding yams wound around an elastic core yarn in S- and Z-direction. From Schwarz, A., Kazani, I., et al., 2011. Electro-conductive and elastic hybrid yams— the effects of stretching, cyclic straining and washing on their electro-conductive properties. Mater. Des. 32 (8), 4247-4256.

Metal Threads. Metal threads, not really metal fibers but metal filaments, are human-made. In antiquity, metal threads were made for ornamental or decorative purposes from precious, ductile metals or alloys, particularly silver and gold and their alloys. Such threads were either applied with adhesives to finished fabrics or wound around ordinary textile yam cores the metal-covered yarn was then either woven into textile fabrics or embroidered on the textile fabric (Jaro and Toth 1991 Lee-Whitmann and Skelton 1984). 

Safety fuses are used for the direct ignition of propellants, pyrotechnics, and primary explosives. A safety fuse is composed of a black powder core, three layers of cotton or jute yarn wound around the core, bitumen impregnation, and plastic coating. The burn rate for a safety fuse is usually around 120 + 10 seconds/meter. 

Figure 12.17 Photomicrograph of tricot knitfabric, made from core/sheath (C/S) bico filament yarn and thermally fused after knitting. Photograph reproduced by permission of KoSa Corporation...

Figure 13.1 Yarn break caused by skin-core differences (brittle fracture and crazes) [9]. Photograph provided by W. Goltner...

The polymer was extruded at 240 C to produce 28-strand multifilament yarn. The yam was hot-stretched and fiber tensile strengths in the range 3-6 g/den (1-2 dpf) could be obtained. The yam was placed on braider bobbins on a 12-carrier machine with 7-ply core. The braid was made with 51 picks per inch and hot-stretched 25% at215 F. 

CA 53,7598(1959) [Flexible detong fuses, constg of a core(2.85g) of PETN or RDX 0.15g of Na carboxymethylcellulose or Na alginate per ft of fuse, are enclosed in a paper tube and wound with jute cotton yarn. A coating of wax or bitumen at 100° a waterproof coating of polyethylene are then/applied 249)H.P. Jenkins s/c.H.Shomate,USP 2865726(1958) ... 

By itself a subject of study, metallic yam used in the past comes in a number of varieties that reflect the level of technology and trade of the time. A majority of metallic threads has been made into yarn by cutting prepared metallic material into strips that were then wound around a core thread of silk or linen. The metallic materials used were either gold or silver leaf adhered to membrane, parchment, leather, or paper or plain soft metal. Membrane is adversely affected by water and... 

The length of the fuse will depend on the safety period required. The structure of the fuse comprises (proceeding from the fuse interior outwards) a black powder core with one or two marking threads, the color of which indicates the identity of the manufacturer, two or three layers of yarn wound around it (jute, cotton, or some other yarn), a bitumen impregnation, and a plastic coating. 

Elemental maps of the metal-wrapped linen (TSM 13.1919) showed that the metal wrapping was silver, but the fibers in the yarn also contained some silver and calcium. The maps of the metal-wrapped silk (MMA 46.156.134) show that the metal wrapping was gold-coated silver, and that calcium was present in the fibers but not silver. Potassium was present in both the metal wrapping and the fiber core. 

The Etowah fabric bundle (No. 840) contains fine yarns made of bundles of vegetable fibers typical of bast fibers. The core yams of Etowah Mound C (EMC) No. 1145 also are bast, and they are wrapped with feathers. Figure 10 is an electron micrograph of the nodes on the barbules of these feathers. The copper plate EMC No. 1156 contains a twisted yarn of undetermined fiber composition the fibers are smooth, untwisted, and long. Perhaps they are hair, but no scale structure was apparent on their surfaces. In the same area of the plate, some loose fibrous material adjacent to the yam proved to be feather. In a second area of the plate, some fibrous material of undetermined type similar in appearance to that in the first area is present. 

C. In each a core of yarns appears to be wrapped with featherlike structures, which are then bound to the core by a fine yam with no twist (Figure 12). System A yams measure 4.20 mm the featherlike structures exhibit the characteristic shapes of downy barbules found on feathers, as indicated earlier. Scholtz (12) considers the complex yarns to be re-plied yams because the core consists of plied yams, and a wrapping yarn encircles the core unit. Modem textile specialists would classify yams... 

Figure 12. Re-plied yarn consisting of core with feather wrapped around it and held in place with binder, No. 1145, Mound C, Etowah, 6X.

Of the three fabric examples from Etowah, the two with the more complicated yarn fabrication exhibit less in elaboration of fabric structures than does the one incorporating a simple two-ply, S-twist type of yam. Both the re-plied, feather-core-binder yam of No. 1145 and the eagle plate yam of No. 1156 give little evidence of complex fabric structure. In the feather-core-binder yarn, the clay encrustation obscures fabric structural information. And in the eagle plate yam, only the replied yam and an adjacent fibrous mat remain. 

The Etowah people, like the Spiro people, incorporated feathers into yams with structural permutations beyond what might have been used by the earlier Tunacunnhee-Hopewell people. Unlike the Spiro people, the Etowah people may not have spun down as described by King and Gardner (8), but rather they may have used the perhaps older tradition of core-feather-binder yam to achieve their purposes. The feathers found in the yarns of No. 1145 show no twist or twist direction. 

On the other hand, the loose feathers identified from Etowah No. 1156 could have been spun at one time, but they come from a mat of fiberlike material on which no yam structures currently are evident. Their juxtaposition with the re-plied yam (perhaps of animal hair) presents an anomaly because descriptions (8,12) of other feather yarns do not include a re-plied yam without a bast core. The yam appears to be alike in all its parts. Its color, texture, and surface smoothness suggest an animal-hair fiber. 

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