Chemical fibers melt spinning

Synthetic Fiber and Plastics Industries. In the synthetic fibers and plastics industries, the substrate itself serves as the solvent, and the whitener is not appHed from solutions as in textiles. Table 6 Hsts the types of FWAs used in the synthetic fibers and plastic industries. In the case of synthetic fibers, such as polyamide and polyester produced by the melt-spinning process, FWAs can be added at the start or during the course of polymerization or polycondensation. However, FWAs can also be powdered onto the polymer chips prior to spinning. The above types of appHcation place severe thermal and chemical demands on FWAs. They must not interfere with the polymerization reaction and must remain stable under spinning conditions. 

Early in the manufacture of PP, a concept was developed for dry spinning directly from the solution obtained in the polymerization operation. Had it been feasible, it would have been the realization of a chemical engineer s dream the gaseous olefin fed into one end of the equipment, and the packaged fiber, ready for shipment to a textile mill, coming out the other end. But it did not turn out that way, and today melt spinning is the accepted technique for the production of staple fibers, monofilament, and multifilament yams. To this usual method have been added the fibrillation and the slit film procedures for producing yams. 

Sulfar fibers are extruded from polyphenylene sulfide) or PPS by the melt-spinning process. The first PPS polymer was made in 1897 by the Friedel-Crafts reaction of sulfur and benzene. Researchers at Dow Chemical, in the early 1950s, succeeded in producing high-molecular weight linear PPS by means of the Ullmann condensation of alkali metal salts of p-bromothiophenol. 

Nylon. In 1939 the DuPont Company introduced the first truly synthetic textile fiber. Dr. Wallace Carothers invented nylon as a result of his basic research into polymer science. Chemically, nylon is a polyamide fiber. The two major types of nylon polymer are used in textiles type 6,6 which is made by using hexam-ethylene glycol and adipic acid, and type 6, which is made by polymerizing e-caprolactam. Nylon fibers are made by melt-spinning the molten polymer. The result is a continuous filament fiber of indeterminate length. It is spun in many deniers, with its diameter varying from 10 to 50 microns. The cross-section usually is round, trilobal, or square with hollow channels when used as carpet fiber. 

Hollow membrane fibers are required for many medical application, e.g. for disposable dialysis. Such fibers are made by usmg an appropriate fiber spinning technique with a special inlet in the center of the spinneret through which the fiber core forming medium (liquid or gas) is injected. The membrane material may be made by melt-spinning, chemical activated spinning or phase separation. The thin wall (15-500 xm thickness) acts as a semi-permeable membrane. Commonly, such fibers are made of cellulose-based membrane materials such as cellulose nitrate, or polyacrylonitrile, polymethylmethacrylate, polyamide and polypropylene (van Stone, 1985). 

Melt-spinning ol SiC-snspensinns and the chemical conversion ol C-fibers have minor commercial impoilancc... 

Polyolefin textile fibers are usually produced through the melt spinning process with good mechanical properties and chemical and abrasion resistance. One of the main drawbacks in this industry is the fact that they are difficult to dye unless additives are used. One of the major applications of PP is the use in carpet which replaced natural fibers. Other apphcations include bags, sportswear, and knitwear. 

S Houis, N Schedukat, T Cries, PVDF melt spinning of trilobal shaped, hollow fiber and fine multifilament yam , Chemical Fibers International, 2007 57 122-123. 

Fiber-forming thermoplastic polymers are processed by spinning into filaments, which in turn are made into yarn, tow, roving, staple, and cord. The three principal types of spiiming processes, namely, melt spinning, dry spinning, and wet spinning are also discussed in Chapter 1, with a focus on the physico-chemical factors of the respective processes and their effects on end-product qualities. 

Commercial wire drawing processes produce metal wires with round cross sections but they are highly energy and labor intensive. Wire drawing falls outside the scope of this book. Commercial rapid solidification processes yield amorphous metallic ribbons. Inviscid melt spinning yields metal fibers by a chemically assisted jet stabilization process. 

F. T. Wallenberger, N. E. Weston, K. Motzfeldt, and D, G. Swartzfager, Inviscid melt spinning of alumina fibers chemical jet stabilization, Journal of the American Ceramic Society. 75 [3], 629-639 (1992). 

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