**1. Introduction**

154 Woven Fabrics

Zhang, C. Gopalakrishnan, S. (1996). Fractal geometry applied to on line monitoring of

Synthetic fiber industry has been enforced to make developments due to the increasing performance demand for textile products. One of the most important developments in synthetic fiber industry, is absolutely producing extremely fine fibers which are named as microfibers and nanofibers (Kaynak & Babaarslan, 2010). Until today, there is no exact definition for microfibers. But common opinion is defining a fiber finer than 1 dtex or 1 denier as microfiber (Leadbetter & Dervan, 1992; Bianchi & Maglione, 1993; Purane & Panigrahi, 2007; Basu, 2001; Mukhopadhyay, 2002; Falkai, 1991; Rupp & Yonenaga, 2000). 1 dtex polyester fiber has a fiber diameter of approximately 10 µm (Falkai, 1991). On the other hand, nanotechnology refers to the science and engineering concerning materials, structures and devices which at least one of the dimensions is 100 nanometers (0.1 µm) or less (Ramakrishna, et al., 2005).

Fabrics produced from microfilaments are superior to conventional fiber fabrics, due to their properties such as light weight, durability, waterproofness, windproofness, breathability and drapeability. Tightly woven fabrics produced from microfilament yarns have a very compact structure due to small pore dimensions between the fibers inside the yarns and between yarns themselves. These fabrics provide very good resistance against wind for different end uses such as parachutes, sails, wind-proof clothes, tents while serving light weight and high durability properties (Babaarslan & Kaynak, 2011). Wind resistance is usually assessed by measuring air permeability. This is the rate of air flow per unit area of fabric at a standard pressure difference across the faces of the fabric (Horrocks & Anand, 2004). Airflow through textiles is mainly affected by the pore characteristics of fabrics. The pore dimension and distribution in a fabric is a function of fabric geometry (Bivainyte & Mikucioniene, 2011). So, for woven fabrics, number of yarns per unit area, yarn linear density, weave type, fabric weight and fabric thickness are the main fabric parameters that affect air permeability (Fatahi & Yazdi, 2010; Çay & Tarakçoğlu, 2007; Çay & Tarakçoğlu, 2008; Turan & Okur, 2010). On the other hand, considering the yarn structure; yarn production technology, yarn diameter, yarn twist, hairiness, being staple or filament yarn, fiber fineness, fiber cross-section and yarn packing density are also important parameters (Turan & Okur, 2010). The pores of a fabric can be classified as pores between the fibers inside the yarns and between yarns themselves. The dimensions of the pores between the yarns are directly affected by the yarn density and yarn thickness. By increasing of the yarn density, the dimensions of the pores become smaller, thus the air permeability decreases.

Yonenaga, 2000). This was the first attempt to produce an ultra fine fiber intentionally. Matsui et al. of Kanebo also tried multi layer conjugate spinning in 1968 for the production of ultra fine filaments. Since no application of ultra-fine fibers was foreseen in the 1960s, there had been no technical or commercial interest in them until Toray put the new suede-

Microfibers are being increasingly used throughout the world for various end uses due to their fineness, high performance characteristics and their unique ability to be engineered for a specific requirement (Anonymous, 2000). Fundamental characteristics of microfibers are as

 Since bending and torsional stiffness are inversely proportional to fiber diameter, ultrafine fibers are extremely flexible (Okamoto, 1993) and for the same reason microfiber yarns impart excellent drapeability to the fabric (Basu, 2001; Purane &

 Yarn strength is high due to the high number of fiber per cross sectional area (Basu, 2001). Microfiber fabrics are also relatively strong and durable in relation to other

 The yarns made from micro denier fiber contain many more filaments than regular yarns producing fabrics with water tightness and windproofness but improved

 More filaments in yarn result in more surface area. This can make printed fabrics more clear and sharp as compared to normal fabrics (Basu, 2001). Greater fiber surface area

Microfiber fabrics are very soft and have a luxurious hand with a silken or suede touch

Microfibers have a quick stress relief so microfiber fabrics resist wrinkling and retain

Microfiber fabrics insulate well against wind, rain and cold and also they are more

Microfiber dries in one-third of the time of ordinary fibers (Purane & Panigrahi,

One caution related to synthetic microfibers is heat sensitivity. Because the fiber strands are so fine, heat penetrates more quickly than thicker conventional fibers. So, microfiber fabrics are vulnerable to damage from careless ironing. They will scorch or glaze if too much heat is

They also have a tendency to snag easily and, as with all fine fabrics, they need to be handled with care. Jewelry cause pulls, snags or general abrasion to garments (Smith, n.d.; East, 2005). Since microfibers have an increased surface area, resulting in a dyeing rate four times higher than that of normal which can cause unlevelness in dyeing. They require more dyestuff than

results making deeper, richer and brighter colors possible (Smith, n.d.).

Microfibers are super-absorbent, absorbing over 7 times their weight in water

A large ratio of length to diameter resulting in easy entanglement

Bio-singularity to living tissues and fluids (Okamoto, 2000).

like material on the market in 1970 (Okamoto, 2000).

Panigrahi, 2007; Rupp & Yonenaga, 2000)

breathability (Basu, 2001).

fabrics of similar weight (Purane & Panigrahi, 2007).

(Rupp & Yonenaga, 2000; Purane & Panigrahi, 2007).

shape (Purane & Panigrahi, 2007; Okamoto, 2000). Microfiber fabrics are washable and dry-cleanable

breathable and more comfortable to wear

Good interpenetrating capacity to other materials

applied for a too long period (Smith, n.d.; East, 2005).

follows;

2007).

The dimensions of pores between the fibers inside the yarns (micro voids) are generally affected by fiber fineness, yarn count, yarn twist and crimp and also the deformation and flattening of the yarns (Çay & Tarakçoğlu, 2008).

In an earlier study (Varshney et al., 2010), the effect of filament fineness on air permeability of polyester and polyester/viscose woven fabrics was observed. It was seen that decreasing filament fineness has a decreasing effect on air permeability. An another study, (Laourine & Cherif, 2011) was performed on the effect of filament fineness and weave type on air permeability of polyester woven fabrics for surgical protective textiles. The study showed that air permeability can be reduced by decreasing the filament fineness. Also, for woven fabrics with nearly same degree of cover factor, lower levels of air permeability can be reached with plain weaves than those of twill weaves. Kaynak & Babaarslan (2011), investigated the filament fineness on polyester woven fabrics for plain weave. As a result of this study, lower air permeability values were obtained by decreasing the filament fineness. The present study investigates the effects of filament fineness, weft sett and weave type on air permeability of polyester microfilament woven fabrics in a more detailed manner, aiming to determine the proper construction parameters of fabric. In addition regression analyses were conducted to estimate the air permeability before production.
