Multifilament yarn

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Bundle Preparation. Packages of multifileiment yarns are backwound to prepare bundles necessary for the manufacture of a reverse osmosis module. A proprietary winder for this operation has been designed and constructed at Albany International Research Co. This device is capable of helically winding multifilament yarns into bundles around a mandrel. This is done in a manner such that the resulting bundle has uniform cylindrical dimensions and uniform fiber density. This minimizes channeling and optimizes exposure of membrane surface area. 

Many Quantro II membranes varying incrementally in composition have been under test for 18 months at Albany International Research Co. Tests are performed on experimental samples of fiber. Approximately 16 inches of multifilament yarn are typically subjected to various feeds and conditions. Such a yarn sample is embedded in epoxy which is sealed into a pressure system. Several test facilities are in operation to provide various feeds and conditions. 

Research effort at Albany International Research Co. has developed unit processes necessary for pilot scale production of several species of reverse osmosis hollow fiber composite membranes. These processes include spin-dope preparation, a proprietary apparatus for dry-jet wet-spinning of microporous polysul-fone hollow fibers, coating of these fibers with a variety of permselective materials, bundle winding using multifilament yarns and module assembly. Modules of the membrane identified as Quantro II are in field trial against brackish and seawater feeds. Brackish water rejections of 94+% at a flux of 5-7 gfd at 400 psi have been measured. Seawater rejections of 99+% at 1-2 gfd at 1000 psi have been measured. Membrane use requires sealing of some portion of the fiber bundle for installation in a pressure shell. Much effort has been devoted to identification of potting materials which exhibit satisfactory adhesion to the fiber while... 

In Vitro and In Vivo Degradation of Pofy(Lrlactide) Braided Multifilament Yarns... 

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. 

Knowing the deleterious effects of ionising radiations on PTFE, much attention was paid on their effects on PVDF although the latter had been told to behave well under irradiation. As an example, PVDF multifilament yarns can be y irradiated up to the absorption of 80 kGy without any effect on their Young s modulus [38], However, the structure of the polymer was somewhat modified as its energy to break kept constant and even increased by about 50% while the adsorbed dose was less than 8 kGy but decreased for higher adsorbed doses, down to 1/3 of its maximum value (1/2 of its initial value) when the adsorbed dose reached 81 kGy. To avoid these bulky effects, the interest of... 

P. Marmey, M.C. Porte-Durrieu, C. Baquey, PVDF multifilament yarns grafted with polystyrene induced by gamma-irradiation Influence of the grafting parameters on the mechanical properties, Nucl. Instrum. Methods Phys. Res. B 208 (2003) 429-435. 

Monofilament yarns consist of a single filament. The filament size is much larger than those found in multifilament yarn. Consequently, monofilament is relatively stiff and is used mainly for the production of rope and twine. Fiber size range is typically 75 to 5000 denier. Monofilament fiber is usually produced from polypropylene homopolymer with a relatively low melt flow index in the range 3.5 to 5.0 grams/10 min. 

Herculon [Aqualon], TM for polypropylene olefin fibers. Available in bulked continuous and continuous multifilament yarns, staple, and uncut tow. 

Lenzing PTFR [Lenzing AG] FIFE for multifilament yarns in sealing industry, staple fibers, weaving yam, and sewi threads in filter industry, films in the cable industry. 

In 1981, about one third of the total polypropylene usage was based on conventional staple and multifilament products about 60 KT (thousand tons) of ST and 54.5 KT of multifilament yarn. The largest textile end-use of polypropylene was in carpet backing, which was made primarily from ribbon yams. By 1995, its production surpassed aliphatic polyamides (PA) and polyacrylonitrile (PAN), but lagged behind PET. In 2002, the production of polyester fiber was 62%, polypropylene fiber, 17.5%, polyamide fiber, 11.5%, and polyacrylonitrile, 18.1%i, of all synthetic fibers. 

Polypropylene fibers are produced by a larger variety of processes than other melt-spun fabrics. At one end of the range, the long air-quench process produces high-quality multifilament yarns, and, at the other end, fibrillating slit film produces coarser fibers. The success of the lower-cost polypropylene slit-film fiber is due to the lower price of the polypropylene resin and the unique adaptability of polypropylene to the less expensive slit-fibn fibrillation process. The water-quench process for monofilament has long been an established technique... 

Chardonnet, however, has the distinction of being the first to produce multifilament yarns by forcing a cellulose solution through very small holes in a spinnerette and to produce and market rayon. He was awarded the Perkin medal in 1914 for this achievement. 

The number of filaments in a yarn may vary from a single monofilament to thousands of filaments in multifilament yarns. Some carbon fibre rovings consist of 50,000 filaments. 

Polyester (PES or PET), high tenacity polyester (PES FIT), glass (G) EC6 means continuous E-glass multifilament yarn of 6 pm diameter for each filament polytetrafluoroethylene (PTEE). 

Fig. 3.18 Scanning electron micrograph showing multifilament yarn.

Figure 2. SEM micrographs of a woven fabric made of PET monofilaments (left) and of a woven fabric made of polyamide multifilament yarn (right).

Ill) The capillary system, especially of fabrics made of multifilament yarn, provokes the penetration of a sessile droplet. Especially in the case of substrates which are not very hydrophobic, there will not be a real equilibrium ... 

As a result, the strength level for a stoichiometric or 100% converted silicon carbide yam was reported to be 1.11 GPa (uncoated) and 1.60 GPa (coated), and that for a 90% converted yarn was reported to be 1.70 GPa (uncoated). The individual silicon carbide fibers, multifilament yarns and fabric samples which were obtained were suitable for evaluation of mechanical properties from room temperature to 1500 C. A commercial process for the fabrication of continuous multi-filament silicon carbide yarns by this route has not yet been reported [29]. 

Two of the four known silica giass fiber processes are dry spinning processes. They are continuous processes, which afford either a continuous sliver or staple product, i.e., a cohesive array of discontinuous fibers, or a continuous multifilament yam, respectively. The other two processes are continuous processes yielding continuous fibers and multifilament yarns. Of these, the preform process (Chapters 4 and 6) relies on the use of silica preforms, and produces continuous, ultrapure siiica giass fibers, or quartz fibers. This process yields the strongest silica giass fibers on record. 

Commingled yarn ko- mig-gol, ka- (ca. 1626) V. In aerospace textiles, two or more continuous multifilament yarns, the filaments of which have been intermixed with each other without adding twist or otherwise disturbing parallel relationship of the combined filaments. Usually consists of a reinforcing yam, such as graphite or glass, and a thermoplastic matrix yarn. 

Multifilament yarn n. A manufactured yarn composed of many fine continuous filaments or strands. 

Twist n. (1) A textile term, the number of turns (360°) per unit length that a multifilament yarn, staple yarn, or other structure is turned or twisted around its longitudinal axis into a stable structure. (2) The unintended, progressive spiraling seen in some protruded products. 

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