Yam processing

In the textile industry, yam spinning was one of the very first processes to be industrialized. Spun yams may contain a single type of fiber or a blend of various types. Combining synthetic fibers (which can have high strength, luster, and fire-retardant qualities) with natural fibers (which have good water absorbency and skin-comforting qualities) is very common. The most widely used blends are cotton-polyester and wool-acrylic fibers. Blends of different natural fibers are common too, especially with more expensive fibers such as cashmere. Yams are selected for different textile products based on the characteristics of the constituent fibers, such as wool for warmth, nylon for durability, cashmere for softness, etc. 

Technically, yams are made up of a number of singles, which are known as plies when grouped together. These singles of yam are twisted together in the opposite direction to make a thicker yam. Depending on the direction of the final twist, the yam can be S-twist or Z-twist. 

Filament yam consists of filament fibers either twisted together or simply grouped together, hi order to develop stretch and bulk in subsequent processing, filament yams are often texturized. When woven or knitted into fabric, the cover, hand, and other aesthetics of finished fabrics made from texturized filament yams resemble the properties of a fabric constracted from spun yam. 

Air-jet method In this method, yarn is led through the turbulent region of an air jet at a rate faster than it is drawn off on the far side of the jet. In the jet, the yam stracture is opened, loops are formed, and the structure is closed again. Some loops are locked inside the yam and others are locked on its surface. 

Gear-crimping method In this method, yam is fed through the meshing teeth of two gears. The yam takes on the shape of the gear teeth. 

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The air jet textured yam process is based on overfeeding a yam into a turbulent air jet so that the excess length forms into loops that are trapped in the yam stmcture. The air flow is unheated, turbulent, and asymmetrically impinges the yam. The process includes a heat stabilization zone. Key process variables include texturing speed, air pressure, percentage overfeed, filament linear density, air flow, spin finish, and fiber modulus (100). The loops create visual and tactile aesthetics similar to false twist textured and staple spun yams. 

Modified Viscose Processes. The need for ever stronger yams resulted in the first important theme of modified rayon development and culminated, technically if not commercially, ia the 0.88 N/tex (10 gf/den) high wet modulus iadustrial yam process. 

High Tena.city Sta.ple Fibers. When stronger staple fibers became marketable, the tire yam processes were adapted to suit the high productivity staple fiber processes. Improved staple fibers use a variant of the mixed modifier approach to reach 0.26 N /tex (3 gf/den). The full 0.4 N /tex (4.5 gf/den) potential of the chemistry is uimecessary for the target end uses and difficult to achieve on the regular staple production systems. 

From a quantitative study of the effect of lubricating oils in static generation by yams, the role of dynamic coefficient of friction was compared with that of electrical conductivity (85). In order to avoid static difficulties in yam processing, the yams must have a low coefficient of friction and, more importantly, have the highest possible conductivity. Whatever the coefficient of friction may be, the voltage approaches zero if the conductivity becomes high enough (85). 

Hydrolene H, S. [Lenox] Nonionic organic ester hygroscopic agent and lubricant in yam processing. 

As in the production of the fabrics for dust collection applications, heat is again instrumental in inducing the necessary fabric stability, which, on this occasion, may be achieved through hot aqueous treatment, heat setting, or a combination of both. In the case of aqueous treatmeuts, these may also include surfactants to remove unwanted fibre and yam processing aids. Once again, media manufacturers will be aware of the machine speeds and tanperatures that will be necessary in these processes in order to achieve the maximum effect... 

Uses Conditioner, antistat, film-former, emollient in cosmetics, hair shampoos, conditioners, rinses, moisturizing creams, lotions, bath prods., skin care flocculant/coagulant for water clarification, potable water treatment, wastewater treatment, oil field, flotation enhancement, mining filtration aid coagulant for yam processing. 

Mader, E., Rausch, J., Schmidt, N., 2008. Coimningled yams - processing aspects and tailored surfaces of polypropylene/glass composites. Compos. Part A 39, 612-623. 

Mader E, Rausch J, Schmidt N. Commingled yams — processing aspects and tailored surfaces of polypiopylene/glass composites. Compos Part A Appl Sci Manuf 2008 39 612-23. 

Table 9.9 Emission and consumption data from the textile yam process [4, APME, 2004]...

A diagram depicting the process is given in Figure 1.5. The underlying principle of this process closely resembles the rotating dual-collector yam process patented by Formhals in 1934 [105]. 

The self-assembled yam process was developed by Ko [109] at Drexel University. When a solution of pure polymer, or a polymer-containing polymer blend, was electrospun onto a solid conductive collector under appropriate conditions, the fibers did not deposit on the collector in the form of a flat nonwoven web as is usually observed. Instead, initial fibers deposited on a relatively small area of the collector and then subsequent fibers started accumulating on top of them and then on top of each other,... 

Cogswell, F. N. (1975), Polymer melt rheology during elongational flow , in White, J. L. Fiber and Yam Processing, Appl Polym Symp No. 27, John Wiley Sons Inc. 

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