Lycra fiber

With the aim of minimizing investment and operating costs, EhiPont s approach included an integration of the process for MA from -butane with aprocess employing the MA obtained to directly produce tetrahydrofuran (used for the manufacture of lycra fibers) in the same production plant, in order to replace the Reppe method with a new process and with minimized CO2 emissions. The DuPont process was initially commercialized in 1996 in a plant on Gijon, Spain. However, due to several operational problems, the plant was closed in 2004. ... 

Technically, the elastic stocking consists essentially of a transverse weft thread which produces the compression. The weft thread is made of natural rubber or elas-tane (Lycra fibers), which is usually double wrapped with threads such as cotton, polyamide, or microfiber polyamide so as to fix the weft thread itself at a predetermined tension and produce the physical and esthetic characteristics of the stocking. The knit through which the weft thread passes consists of elastic yams, of lower strength compared with the weft, usually woven with the method known as crossed and locked knit. 

Use of 1,3 cycloaHphatic diamines in polyamides may be similarly limited by internal amide dehydration of the conformationaHy labile cis isomers to form a tetrahydropyrimidine (38) rather than high molecular weight polyamide. 1,3-Cyclohexanediamine is, however, a component of Spandex polyureas Du Pont uses the hydrogenation product of y -phenylenediamine [108-45-2] (24) captively to produce Lycra (see Fibers, elastomeric). 

DuPont and Shell have developed a new polyester, poly(trimethylene terephthalate) (PTT) (structure 19.38) that is structurally similar to PET, except that 1,3-propanediol (PDO) is used in place of ethylene glycol. The extra carbon in Sorona allows the fiber to be more easily colored giving a textile material that is softer with greater stretch. Further, it offers good wear and stain resistance for carpet use. The ready availability of the monomer PDO is a major consideration with efforts underway to create PDO from the fermentation of sugar through the use of biocatalysts for this conversion. Sorona and Lycra blends have already been successfully marketed. Sorona is also targeted for use as a resin and film. 

Figure 7.6 SEM micrograph of knitted cotton/Lycra fabric (original magnification 600x) Cotton fibers dominate the image. (Photo R. C. Janaway.)...

We all use spandex, that extremely stretchable fiber known as elastane in Europe or called Lycra if manufactured by DuPont It provides the "stretch" in panty hose and other undergarments, swimsuits, jeans, cycling shorts, tights, and many other articles of clothing. 

Elastane. The DuPont Company commercialized the first manufactured elastic fiber, Lycra, in 1958. Originally categorized as a span-dex fiber, the name elastane has become more common around the world. This specialty fiber is described as a segmented polyurethane that contains hard and soft segments their ratio determines the amount of stretch built into the fiber. Elastane fibers are formed by dry-spinning or solvent-spinning. The continuous filaments can be coalesced multifilaments or monofilaments, depending on the manufacturer. 

Fibers ", Wool, Silk, Cellulose Nylon, PET, Lycra ... 

In much the same way, natural polymeric fibers like wool, cotton, silk, etc., are often touted as superior to anything that is man-made or synthetic. But is this fair There is no doubt that natural fibers have a unique set of properties that have withstood the test of time (e.g., it is difficult, but not impossible, to match silk s feel or cotton s ability to breathe ). On the other hand, consider Lycra , a completely synthetic fiber produced by DuPont (Figure 1-12) that has a truly amazing set of properties and is the major component of Spandex (a material that keeps string bikinis on ). Or consider the wrinkle-free polyester fibers used in clothing and the stain proof nylon and polyacrylonitrile polymers used in carpets. The point here is that polymers, be they natural" or synthetic, are all macromolecules but with different chemical structures. The challenge is to design polymers that have specific properties that can benefit mankind. 

Figure 4.8 cont.) (b) Specific stress-strain curves of Lycra (Spandex) and natural rubber fibers (Wilson, 1967,1968). 

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