Geotextiles

There are several different processes and polymers used in the manufacture of geotextiles which affect their appearance and physical properties. Geotextiles are produced in various weights and thicknesses, which also determine their physical properties and ultimately the performance of the material when installed on a project (see also high performance fibers). 

Geotextiles may be woven, nonwoven, or knitted. All types, woven, nonwoven, or knitted, are susceptible to degradation owing to the effects of ultraviolet light and water. Thus stabilizing agents are added to the base polymeric material to lessen the effects of exposure to ultraviolet light and water. 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

Fabrics perform one or more function in each installation generally there is one primary function. The five basic primary functions have been identified as separation, stabilization, reinforcement, filtration, and drainage. When the geotextile is impregnated with an impermeable material such as an asphaltic 

A xenon arc test of fading resistance also demonstrated that PLA fibers perform better than PET fibers, with a 0% loss in elongation at break for the PLA fibers and a 30% loss in elongation at break for the PET fibers, after lOOh of xenon arc exposure [4]. The superior resistance to exposure to daylight with rainfall and UV is an attractive feature that brings promise for potential outdoor applications such as in agricultural, horticultural, geotextile, and industrial areas. 

FIGURE 29.10 Test results for flammability of the fabrics of PLA and PET in accordance with the Federal Safety Standards for Vehicles FMVSS 302. 

FIGURE 29.11 Accelerated weathering test result of PLA and PET fibers by Sunshine Weather Meter. 

Many fiber manufacturers, in collaboration with their customers, have been developing market applications for PLA fibers. Government efforts will drive further market acceptance, because PLA is viewed as an alternative material to reduce greenhouse gas emissions. The following sections discuss various applications of PLA fibers and the specific properties related to these applications. 

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Nonwoven geotextile Nonwoven sheets Nonwoven textiles Nonwoven wipes... 

Wound dressings Woundhealing Woven fabrics Woven geotextile... 

Olefin fibers are used for a variety of purposes from home furnishings to industrial appHcations. These include carpets, upholstery, drapery, rope, geotextiles (qv), and both disposable and nondisposable nonwovens. Fiber mechanical properties, relative chemical inertness, low moisture absorption, and low density contribute to desirable product properties. Table 7 gives a breakdown of olefin fiber consumption by use (73—75). Olefin fiber use in apparel... 

Olefin fiber is an important material for nonwovens (77). The geotextile market is stiU small, despite expectations that polypropylene is to be the principal fiber in such appHcations. Disposable nonwoven appHcations include hygienic coverstock, sanitary wipes, and medical roU goods. The two competing processes for the coverstock market are thermal-bonded carded staple and spunbond, both of which have displaced latex-bonded polyester because of improved strength, softness, and inertness. 

Polyesters are also used in continuous filament spunbonded nonwovens (see Nonwoven fabrics). Reemay spunbonded fabric is composed of continuous filament PET with a polyester copolymer binder. These spunbonded fabrics are available in a wide range of thicknesses and basis weights and can be used for electrical insulation, coated fabric substrates, disposable apparel for clean rooms, hospitals, and geotextiles (qv). 

Fig. 1. Schematic drawings of five types of geotextile fibers (a) monofilament, (b) multifilament, (c) staple fibers, (d) staple yam, and (e) sHt film.

Fig. 2. Photomicrographs of geotextiles made by various methods (a) woven geotextile, (b) needle-punched, (c) heat-bonded, and (d) resin-bonded.

Separation. In this function, the geotextile serves to separate two dissimilar materials (Fig. 3), eg, two different soils, landfill material and the native soil, stone material and subgrade sod, old and new pavement, foundation sods and various types of wads, or one of many other similar situations. In some instances, it is difficult to distinguish between the separation and stabilization functions because in both situations the geotextde is serving as a separator. However, in stabilization some additional phenomena occur. 

Moisture Barrier. When impregnated with an asphaltic emulsion, geotextiles become impermeable and can then be used as moisture barriers. The primary appHcation for this type of geotextile is in pavement rehabiHtation (Fig. 8). 

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