Multifilament woven fabrics

Monofilament and multifilament woven fabrics are generally made from PET, the use of monofilament giving the better permeabihty, whereas multifilament is used for higher strength reinforcement. SHt film, flat-tape fabrics are usually PP materials, which are quite strong but they form a fabric that has relatively poor permeability. Alternatively, fabrics made with fibriUated-tape yarns have better permeability and more uniform interstice openings than flat-tape products. 

Artificial seaweed tufted into a multifilament woven fabric was developed in 1965 by Sun Oil Co. and used to encourage sand buildup in the seabed and prevent further erosion. Both Nicolon and ICl followed with similar applications in the late 1960s (Brashears and DartneU, 1967). Silt fences, both on sloping gravel surfaces and underwater, were developed by Erosion Control Co., Burlington Industries, and the Mirafi Co. in the late 1960s (Koemer and Welsh, 1980). 

Woven fabrics are usually made with natural or synthetic fibers from three different types of yams monofilament, multifilament, and spun staple, as shown in Figure 22.65. Performances of these three types of yams are shown in Table 22.12. 

Open mesh glass fibre woven fabric Open mesh glass fibre woven fabric Multifilament PTFE woven fabric... 

Multifilament PTFE woven fabric Very good <25 Very good Extreme high end use, especially... 

In general, PET with a high tensile strength, and glass, which both appear as multifilament yams, are used for coated membranes. For load-bearing constructions woven fabrics are mostly qualified twisted multifilaments are processed to plain woven fabrics in plain or in panama weave. 

Woven geotextiles. A woven fabric consists of two sets of orthogonally interlaced filaments or staple-fibre yams. The weave design or pattern is determined by the manner in which yams or filaments are interlaced. Filaments or yams placed in the longitudinal and transverse directions are known as warp and weft, respectively. Monofilament and slit woven geotextiles are anticipated to be thinner in comparison to multifilament, spun, and fibrillated woven geotextiles. 

Figure 2. SEM micrographs of a woven fabric made of PET monofilaments (left) and of a woven fabric made of polyamide multifilament yarn (right).

One of four basic yarn types, shown in Figure 2.2, is normally employed in the production of woven fabrics monofilaments, multifilaments, staple spun yams and fibrillated tape yams (a helpful summary of trade names is given by Purchas and Sutherland, 2002). 

Figure 13.1 Elementary constructions of woven fabrics (a) twUl fabric made of monofils, (b) plain weave fabric made of multifilament yarn, (c) plain weave fabric made of multifilament (warp) and staple fiber yarn (weft), and (d) plain weave fabric made of a twisted multifilament yarn (from [24]).

The special geometry of the fabric may lead to different types of mechanical anchoring processes, associated with effects such as filling of the spaces between perpendicular yarns, which form the fabric, as well as the crimping of the yarns in woven fabric. Thus, the bond of the fabric cannot be simply described and accounted for by the bonding of the individual strands, and there is a need to consider another level of complexity, on top of the multifilament nature of the yarn,... 

Woven fabrics are then made up from single filaments, or multifilament yams, or from twisted staple yam. The last of these is normally used as a single strand, but two or more spun strands may be combined into ply yams, where the strands are twisted together, usually (but not necessarily) in the opposite sense from the twist in each strand. 

Fabrics are divided into three different types of yams monofilament, multifilament, and spun. They can be composed of more than one of these types of bric. Monofilaments are composed of single strands woven together to form a translucent or opaque febric. Very smooth in appearance, its weave is conducive to eliminating blinding problems. 

Most CMCs are reinforced with continuous, multifilament tow ceramic fibers. Fiber tows typically consist of 500 to 1,000 filaments, with a diameter of 10 to 15 pm (0.40 to 0.59 mils) each. These fiber tows are flexible, easy to handle, and can be woven into fabrics and used to fabricate complexshaped composites. Monofilament fibers have also been used to reinforce ceramic composites, but they have several disadvantages. For example, monofilaments (espeeially singleerystal fibers) are expensive, and their large diameter (> 75pm [3.0 mils]) limits their minimum bend radius, whieh ean make fabricating complex-shaped composites difficult. This chapter, therefore, focuses on small diameter, multifilament eeramie fibers. 

Staple-fibre yams - at least in the weft direction. In operation, the fabric is pulled over a series of rotating rollers termed pile and connter pile , each of which is clothed with card wire and monnted concentrically on a large cylinder of approximately 1.5 m diameter. As the cylinder rotates, the pile rollers raise the fibres proud of the surface, whereas the counter pile rollers stroke them into a more orderly fashion. Raised fabrics may comprise 100% staple-fibre yams or a combination of multifilament and staple-fibre yams, the latter being woven in satin style in which the face side is predominantly multifilament yams and the reverse side predominantly of staple-fibre yams. The smooth surface provided by the multifilaments will aid cake release, whilst the raised staple-fibre yams on the reverse side will enhance the particle collection efficiency. A significant measure of the width contraction invariably takes place during this operation and proper attention will have to be given to this when designing the fabric. 

Fig. 3.24 Scanning electron micrograph showing fabric woven with multifilament (warp) and woollen ring-spun (weft) yams.

This is the most basic weave of all woven stractures that provides the framework for the tightest and most rigid of all single-layer filter fabrics (see Fig. 3.19). Because of the sinusoidal path that the yams follow, this weave is particularly suitable for flexible yams of the multifilament and short staple-fibre types. The weave is also ideally suited to applications where thread displacement, due for example to high internal pressures, may otherwise be experienced. 

Whilst this amount covers all filtration media, the textile fabrics used for the filter media have worldwide sales of more than US 3 billion. Woven filter fabrics made from both multifilaments and monofilaments have dominated the filtration market for both wet and dry applications. However, the recent developments in nonwoven technology have allowed the process to gain market share due to cost, disposal, and production advantages. ... 

Each fabric has its own particular characteristic vtiiich can be used to advantage in the filtration process. Thus the smooth-surfaced mono- and multifilament (high-twist) cloths are particularly suited to the liquid environment, in the separation of sticky, clogging substances such as sludges or colloids. Retention of such small material depends on a rapidly formed surfece layer of particulates in the reported use of monofilament polyamides for effluent treatment plants [Grove Daveloose, 1982]. Apparently in this application, change firom q>un fibre to woven cloth increased the cloth lifetime from 3 months to 2.5 years The adhesive nature of such solids may be modified by treatment with polyelectrolytes. Quite opposite results can also be experienced, however, where the three-dimensional capture characteristics of staple fibre material is the best option. 

A series of tubular fabric samples, typical for use in endovascular prostheses, were woven from polyester monofilament and multifilament yams on a special narrow ribbon shutde loom. They were 8 mm in diameter and 6 cm in length, and bad the structural specifications listed in Table 1. 

The suture is woven into fibers in order to maximize the resulting stroigth. For materials that possess a high tensile modulus, yams composed of low-denier filaments are bricated into a multifilament braid in order to achieve adequate suppleness. Materials that a tensile modulus of about 500 kpsi or less can be fabricated into... 

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