Yarn

Filament yarns can be classified by the products into which they are converted as seen in Fig. 1.10. 

Typical fineness 1000,1500,2000 dtex, - 20 den Aerodyn. crimper-textured Spin-draw texturing process 

Technical yarns - Tire cord, industrial yarns, high tenacity type (PA, PET, CV)  

Fineness - 5-10 dtex, untextured, bright Spin-draw process for technical yams (4 godet duos) 

Aramid, Dyneema, etc. Typical yarn fineness 420-9660 dtex with 250-6000 single filaments Single filament fineness approx. 1-2 dtex 

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Viscosity additives are aliphatic polymers of high molecular weight whose main chain is flexible. It is known that in a poor solvent, interactions between the elements making up the polymer chain are stronger than interactions between the solvent and the chain (Quivoron, 1978), to the point that the polymer chain adopts a ball of yarn configuration. The macromolecules in this configuration occupy a small volume. The viscosity of a solution being related to the volume occupied by the solute, the effect of polymers on the viscosity in a poor solvent will be small. 

Stress relaxation studies were conducted on samples of nylon yarn at a constant strain of 2% and the following results were obtained ... 

Antistatic coatings Antistatic finishes Antistatic yarns Antistatin D Antisterility vitamin Antistick agents Antistick applications Anti-Stokes lines... 

POX. See Polyoxetane Poxvindae Poynting correction Poynting factor POY nylon yarn Pozzolans... 

Yarns and Fibers. Many different acetate and triacetate continuous filament yams, staples, and tows are manufactured. The variable properties are tex (wt in g of a 1000-m filament) or denier (wt in g of a 9000-m filament), cross-sectional shape, and number of filaments. Individual filament fineness (tex per filament or denier per filament, dpf) is usually in the range of 0.2—0.4 tex per filament (2—4 dpf). Common continuous filament yams have 6.1, 6.7, 8.3, and 16.7 tex (55, 60, 75, and 150 den, respectively). However, different fabric properties can be obtained by varying the filament count (tex per filament or dpf) to reach the total tex (denier). 

Yarn drying procedures are far more critical than staple drying procedures. AH ceUulosic fibers expand when wetted and contract on drying, the... 

The selection of twist level is important not only in estabUshing the surface characteristics of the yam, eg, low twist for soft, fuzzy yams and high twist for compact, smooth yams, but also in determining yam strength. Yarn strength as a function of yam twist level is shown in Figure 1. 

Yarn grade is assessed using ASTM D2255, which is a subjective test requiring the evaluation of yam wound on a board. More recendy a method has been introduced to assign a yam grade quantitatively (115). 

Knitted fabric constmction characterization is discussed in ASTM D3887. Characterization of knitted fabrics includes yield (area per weight), width, length, and yam count (number of courses and wales per unit length). The type of knit is also specified, eg, warp knit or weft knit. Yarn analysis may be difficult on account of problems in raveling individual yams from the knitted stmcture, particularly warp knits. 

Standard Test Methods for Tire Yarns, Cords, and Woven Fabrics. ASTM standard D885M-94 includes test methods for characterizing tire cord twist, break strength, elongation at break, modulus, tenacity, work-to-break, toughness, stiffness, growth, and dip pickup for industrial filament yams made from organic base fibers, cords twisted from such yams, and fabrics woven from these cords that are produced specifically for use in the manufacture of pneumatic tires. These test methods apply to nylon, polyester, rayon, and aramid yams, tire cords, and woven fabrics. 

Static Adhesion Tests for Organic-Based Yarns, Cords, and Fabrics. The most commonly used static adhesion tests are the H-test... 

Property Yarn Photographic film Plastics Lacquers... 

Type of Data In general, statistics deals with two types of data counts and measurements. Counts represent the number of discrete outcomes, such as the number of defective parts in a shipment, the number of lost-time accidents, and so forth. Measurement data are treated as a continuum. For example, the tensile strength of a synthetic yarn theoretically could be measured to any degree of precision. A subtle aspect associated with count and measurement data is that some types of count data can be dealt with through the application of techniques which have been developed for measurement data alone. This abihty is due to the fact that some simphfied measurement statistics sei ve as an excellent approximation for the more tedious count statistics. 

Introduction The following example data are used throughout this subsection to illustrate concepts. Consider, for the purpose of illustration, that five synthetic-yarn samples have been selected randomly from a production line and tested for tensile strength on each of 20 production days. For this, assume that each group of five corresponds to a day, Monday through Friday, for a period of 4 weeks ... 

Application. In the past, the break strength of a synthetic yarn has averaged 34.6 lb. The first-stage draw ratio of the spinning machines has been increased. Production management wants to determine whether the break strength has changed under the new condition. 

Cloth Blinding Continuous filters, except for precoats, generally use some type of medium to effect the separation of the solid and filtrate phases. Since the medium is in contact with the process solids, there is always the danger, and almost invariably the ac tual occurrence, of medium blinding. The term blinding refers to blockage of the fabric itself, either by the wedging of process solids or by solids precipitated in and around the yarn. 

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