Definition of textured yarn and advantage with classification

Definition: -
                     
                    Continuous-filament yarns are subjected to a modifying process, the purpose of which is to introduce permanent waviness (crimp), loops, coils, and wrinkles and thereby' to modify the geometry of the constituent filaments. In addition, this process also imposes certain structural changes that become apparent in the modified tensile and other related properties of the filaments. This process has the effect of modifying the geometry and structural characteristics of the constituent filaments of a yarn.

Advantage :-

a. Texturizing helps improve the pill and crease resistance and confers better dimensional stability, fuller and better appearance, and greater durability.

b. Textured yarn fabrics have better shape retention ability than those made from straight filament yarns.

c. Flexibility is a very important property desired in textile yarns and fabrics. It depends on the ability of the filament (in the outer layer) to deform (extend) easily. A straight filament is comparatively less flexible than a crimped, looped, and curly filament.
               This ease of deformation of filaments is a function of their bending and torsional rigidities determined by the linear density of the filament and the geometry of the filament in the yarn. In a texturized yarn, filaments lie in all sorts of geometrical configurations and are loosely packed so as not to inhibit their relative movement. This technique confers better flexibility and extensibility to yarns and ultimately to fabrics made from them.
     
              

Stress and strain curves of stretch and bulk yarns (steam -relaxed 2-ply 70/30 nylon yarn) in the crimped region only. 

Load- extension behavior of untextured and textured continues filament nylon yarn.

   d. Texturizing results in softer yarns. Other fa.ctors being equal, the softer the yarn, the better its covering power.

e. Textured yarn fabrics are easy to wash, and they dry readily.

f. They reflect the high abrasion resistance, strength, and toughness of the thermoplastic polymer fibers from which they are made.

 g. Most of the thermoplastic synthetic fibers have very low moisture content as compared to cellulosics and other natural fibers. However, the air entrapped between the interstices of the textured yarns retains moisture and thus makes the texturized yarns have fairly good comfort characteristics.

 h. They provide higher covering power because of increased bulk. 

CLASSIFICATION OF TEXTURED YARNS 

Textured yarns may be classified into three major groups: 

                       I. stretch yarns

                       2. modified stretch yarns or set yarns

                       3. bulk yarns 

Stretch yarn

Stretch yarns are characterized by their high extensibility and good recovery, but possess moderate bulk in comparison with the other two classes of textuced yarns.     

                  Stretch yarns, used extensively in stretch-to-fit garments in w c h extensibility and recovery from stretch are of primary importance, are produced mainly by the false-twist and by the edge-crimping (Agilon®) processes.

Modified stretch 

                              Modified stretch yarns may be defined as those with characteristics inter-mediate between stretch and bulk. yarns. They are produced by modifying the stretch characteristics, usually by an additional heat treatment, after which they retain some stretch but have increased bulk. This modification treatment stabilizes the yarn structure .and its bulk and stretch characteristics. The modified stretch yarns may be produced from stretch yarns by either of the following two methods: 

           I. In one method, stretch yarns may be modified by overfeeding them by as much as 30% or more into a heated zone in which they are stabilized in dry heat (process used on the yarn texturing machine to produce modified "stretch" or "stabilized" yarns).

              2. The stretch yarns may be first soft wound in packages and then heat set or stabilized either in an autoclave in steam or during the dyeing process (the resulting yarns are usually called set yams). 

The modified stretch yarns are used in application which a lower degree of stretch and better hand and appearance are demanded. These yarns are generally used in knitted fabrics because they impart excellent stitch clarity, greater smoothness, and softness of handle, as well as better bulk and low extension under low loads. The iow I-evel of shrinkage of modified stretch yarns has favor-able consequences when their dyeing behavior is considered.


Bulk Yarn

Bulk yarns are characterized by their high bulk with moderate stretch and are used where bulk and fullness of hand are of greater importance than extensibility However, bulked yarns generally possess adequate recovery characteristics. They are mostly used in carpets, upholstery, and garments requiring warmth and comfort characteristics. Bulked yarns are produced by air texturing, stuffer box, knit-de-knit, gear 'crimping, twist texturing, and various other types of crimp texturing  processes. 

Sources:-textile yarns by B.C. Goswami, J.G.Martindale, F.L.Scardino