**4.1 Protection against the weather**

Woven fabrics for protection against the weather were previously coated with polyvinyl chloride in most cases (Rupp & Yonenaga, 2000). But today, closely woven microfilament fabrics offer a new era for protection against weather. As the number of filaments in a yarn of given linear density increases, then the surface area of all the fibers increases and, in a fabric of close construction, the gaps between the fibers become smaller (Richards, 2005).

This method is employed for the production of nonwoven fabrics of polypropylene ultra fine fibers. The polymer melt is blown apart immediately after extrusion by an air jet stream in this method, so it is sometimes termed "jet spinning". Thus, this method is an application of spraying technology rather than true spinning (Okamoto, 2000). It finds applications in an increasing number of fields, such as filtration, absorbency, hygiene and apparel

The polymer is dissolved in transparent solutions at high temperature under high pressure. The spinning solution is jetted out of a nozzle into the air to form a fibrous network. A fiber network is obtained by spreading a single stream of fiber spun from one spinneret hole. The

In this method the conjugate fiber is produced by extruding and drawing a blended polymer melt of two components. The fiber fineness can not be controlled and the fiber often breaks during spinning, although the spinning stability is strongly dependent on the combination of polymers. Since the dispersed polymer phase is drawn to yield ultra-fine fibers, no filament type of ultra fine fiber is produced at present by polymer blend spinning

At the start of the development, the researchers searched intensively for suitable fields of application for their microfibers, since they had not yet existed in previous clothing and technical textile concepts (Rupp & Yonenaga, 2000). Microfibers offer a great variety of applications in fashion clothing owing to their extra softness, full handle, drape, comfort and easy care properties (Anonymous, 2000). One general point that should be mentioned is that the desired properties (i.e. sophisticated handle, pleasant silky appearance, leather lookalike, good filtration properties, etc.) are only obtained when a suitable fabric construction is produced. As well as fineness, the material combination, cross-section of the elementary filaments and their effect when used in combinations are extremely important and can offset negative parameters (i.e. proneness to creasing, somewhat lower absolute tenacity) (Falkai, 1991). Items of polyester microfibers, both 100 percent polyester and blends with other fibers, include coats, suits, blouses, dresses, wall coverings, upholstery, sleeping bags, tents,

Woven fabrics for protection against the weather were previously coated with polyvinyl chloride in most cases (Rupp & Yonenaga, 2000). But today, closely woven microfilament fabrics offer a new era for protection against weather. As the number of filaments in a yarn of given linear density increases, then the surface area of all the fibers increases and, in a fabric of close construction, the gaps between the fibers become smaller (Richards, 2005).

filament thickness varies from 0.01 denier to 10 denier (Okamoto, 2000).

**3.2.1 Melt blowing or jet spinning** 

(Mukhopadhyay & Ramakrishnan, 2008).

**3.2.2 Flash spinning** 

(Okamoto, 2000).

**3.2.3 Polymer blend spinning** 

**4. Applications of microfibers** 

filters and toweling (Kadolph et al., 1993).

**4.1 Protection against the weather** 

They are only very tiny gaps for air to blow through. So, closely woven fabrics are constructed from microfilament yarn which results in small size of gaps to give maximum protection against wind and rain. The use of microfibers ensures that gaps in the fabric are very small even when dry (Mukhopadhyay & Midha, 2008; East, 2005). Moreover, the fabric and fiber surface is enlarged; therefore moisture is transported via more channels, since a better capillary effect is achieved (Rupp & Yonenaga, 2000). This type of weaving results in a windproof fabric with an excellent water vapor permeability compared with laminates and coatings (Mukhopadhyay & Midha, 2008).

Tightly woven microfilament fabrics exhibit an exceptional property of obstructing water droplets from penetrating. Liquid water is prevented by surface tension from penetrating the fabric, which will have a degree of water repellency (Richards, 2005; East, 2005; Anonymous, 2000). These fabrics exhibit an exceptional property of obstructing water droplets from penetrating while allowing water vapor to escape resulting in increased comfort (Anonymous, 2000; Falkai, 1991; Rupp & Yonenaga, 2000). Microfilaments make it possible to structure fabrics so that they repel wind and rain without loosing their textile character. In this respect the low water absorption of polyester plays a part (Basu, 2001). Functionality of densely woven microfilament fabrics with respect to waterproofness and windproofness can be reinforced by hot calendering (Rupp & Yonenaga, 2000). Their improved water impermeability and lower air permeability make microfiber fabrics highly suitable for waterproof and windproof application area such as sportswear, rain clothes, and tents.
