*2.2.1. Polyester*

. Animal

for apparel applications using a process

Flax belongs to the family Linaceae, and the type considered here is from the genus Linum. There are wild-growing, small herbaceous perennials and cultivated annual flax plants. Flax is cultivated worldwide in tropical and cold climate zones. Fiber flax grows in humid, moderate climates, whereas oil flax grows in dry, warm areas. The harvest reaps approxi‐ mately 4000 kg/ha. The fibers are embedded in the parenchyma of the stem in a high concen‐ tration and are freed by retting. Then the flax is washed, dried, and broken to loosen the brittle wood from the bast and to separate the fibers from each other. The wooden parts are removed by means of scotches [6]. Finally, the fibers are combed by means of hackles. The properties of technical fibers and single fibers have to be distinguished. The technical fiber is 200-800 mm in length and composed of a fiber bundle. It has a fineness of about 10-40 dtex. The single fiber has a length of 7-42 mm depending on its location in the stem, its diameter is about 15-37 µm, and the density lies between 1.43 (raw) and 1.52 g/cm3 (bleached). The maturity of the fiber is determined by harvesting time. Good fiber profit with good fiber quality may be obtained at the time of yellow maturity. The relative strength fluctuates between 30 and 55 cN/tex. For all these properties, flax fiber is used for nonwoven bonded fabrics, mostly for the fabrication of

Wool is the most important animal fiber used in manufacturing nonwoven bonded fabrics. It is used mainly as reclaimed wool or cuttings because of its high price. The variation in quality and the impurities in reclaimed wool as well as the chemical and physical properties deter‐

Wool is a suitably stiff and permanently crimped bi-component fiber. The distinct variations in thickness are in most cases favorable to produce nonwovens [16]. Wool fiber is initially used to make felt. The wool fibers are then pressed into a flat sheet and subjected to moisture, heat, and agitation. The scaly structure of the wool fiber causes the fibers to interlock and mat. Weaving or knitting in the production of such felts and simple mechanical interlocking of fibers in the production of such felts and simple mechanical interlocking of fibers in a batt structure

felts have been used since ancient times. Traditional felting method is still used for producing clothing item such as hats, slippers, interlinings and handbags. In addition to traditional felting method, modern pressed felting techniques are used in a wide range of industrial applications. These products are used for polishing metals, optical surfaces plastics, and jewelry, and in manufacturing seals, gaskets, washers, felt nibs and markers, air and liquid filters, oil wicks, piano cushion felts, shoes, toys, pennants, table covers, notice boards, bookbinding, furniture

Wool is not only used for producing felts but also used for producing needle-punched, hydroentangled, thermally and chemically bonded fabrics. In recent years, the production of

known as hydroentanglement has been commercialized. Man-made fibers such as polyester, polypropylene, viscose rayon, and blends containing cotton, wood pulp, and other fibers can

is capable of producing a dimensional stable fabrics with densities, up to 0.7 g/cm3

mined by its provenance impose restrictions on its use [17].

components and orthopedic appliances. [11,18,19].

serviceable, lightweight wool fabrics of 70-150 g/m2

filling pieces [11,16].

*2.1.4. Wool*

6 Non-woven Fabrics

As its name indicates, this type of fiber consists of macromolecules of esters which are chemicals made of acids and alcohol (Figure 3). If many of these basic molecules are combined, they will form polyesters [6].

The earliest study on polyester was conducted by W.H. Carothers at DuPont in the early 1930s, which is comparable to the present-day studies on condensation polymers. Even though a great number of polyesters have been evaluated by now, only a few of them are around that can create good fibers and are crystalline with a melting point between 220 and 280°C, and only three of them gained significance in fiber production [21,22].

Physical properties of polyester fibers are important while producing nonwoven materials. For example, the lengths of cut are adapted to the respective manufacturing procedure. Fibers are also available in different of luster and cross-sectional forms (Figure 4).

They are inexpensive, easily produced from petrochemical sources, and have a desirable range of physical properties. They are strong, lightweight, easily dyeable and wrinkle resistant, and have very good wash wear properties. Therefore, it is mostly used in nonwoven production. Cross-sectional polyester fibers are used in the following three major areas [14]:

**•** Apparel: Every form of clothing;

**Figure 3.** Polyester Fibers [6]

**Figure 4.** Cross-sectional View of Polyester Fibers [23]


Surgeons' gowns,for example, were once woven from linen but are now forthe most part made from repellant-treated entangled polyester fiber pulp composites on spun-bond melt-blown laminates. These new gowns are far superior to the older material in providing a breathable barrier between the surgeon and the patient, which serves to significantly reduce hospital infections. Spun-lace mattress pad facing (100% polyester) continues to be the replacement for spun-bonded material because of the textile-like character of entangled fiber fabrics. Polyeth‐ lene terephthalate (PET) has become the most important polymer type of fibrous prostheses. It is reasonably inert, biocompatible, flexible, and resilient and has an appropriate level of tissue acceptance. However, polymerization initiators, antioxidants, titanium dioxide, and other impurities should be minimized to improve its biocompatibility [14].

Polyester is less flammable than cellulosic fibers because it melts while coming in contact with the flame. Crystar, a DuPont trade name, is used to produce as a polyester spunbond‐ ed fabrics [14].

Among the bi-component fibers, polyester is the most used fiber. Because of its increasing strength and soft hand of the nonwoven fabric, polyester is used in continuous bi-component filaments having a sheath component made of linear low-density polyethylene (PE) and a core component made of polyester. The tensile strength of the fabrics is improved remarkably by the bi-component filaments and depends on the linear low-density polyethylene /polyester ratio. The ultrasonically bonded polyester/polypropylene blend like Matarh's Ultraskin, the protective clothing, is said to protect wearers from rain while offering the breathability needed to provide comfort [24].

Most of the insulation and industrial products are manufactured from synthetic and inorganic fibers by dry- and wet-laid methods. Nonwoven polyester fiber mats are used to produce electrical insulation laminates and electrical tape backing appliances. Polyester and hightemperature-resistant m-aramid nonwoven mats are used as a cost-efficient interchange for aramid paper for insulation composites [25].

Polyester fiber composites are widely used as filtration media. The layers of composite structure give excellent tear strength, a smooth, fiber-free surface, and edge stability. These products supply higher filtration efficiencies than calendared spun-bonded media [26].

Polyester fibers are used inside seat cushions, back pillows, mattresses and waterbeds, decorative and throw pillows, outdoors furniture, and even hand-stuffed custom upholstery in fiberfill applications [27].
