Processing of Fibers

Fiber stmcture is a dual or a balanced stmcture. Neither a completely amorphous stmcture nor a perfectly crystalline stmcture provides the balance of physical properties required in fibers. The formation and processing of fibers is designed to provide an optimal balance in terms of both stmcture and properties. Excellent discussions of the stmcture of fiber-forming polymers and general methods of the stmcture characterization are available (28—31). 

M. Lewin, in M. Lewin and S. SeUo, eds.. Handbook of Fiber Science and Technology Chemical Processing of Fibers andFabrics, Vol. 2, Part B, Marcel Dekker, Inc., New York, 1984, pp. 1—141. 

PE, the united atom model. We considered a sufficiently long PE chain made up of 5000 united atoms under periodic conditions in each direction. The initial amorphous sample prepared at 600 K was quenched to 100 K and drawn up to 400%. The sample was then quickly heated to various crystallization temperatures, and the molecular processes of fiber formation were monitored in situ via the real-space image and its Fourier transform, the structure function S3d([Pg.79]

Wolf, H. J., Shortening of fibers in processing of fiber reinforced thermoplastics, Kunststoffe, 83, 69-72 (1993). 

Control of fiber friction is essential to the processing of fibers, and it is sometimes desirable to modify fiber surfaces for particular end-uses. Most fiber friction modifications are accomplished by coating the fibers with lubricants or finishes. In most cases, these are temporary treatments that are removed in final processing steps before sale of the finished good. In some cases, a more permanent treatment is desired, and chemical reactions are performed to attach different species to the fiber surface, e.g. siliconized slick finishes or rubber adhesion promoters. Polyester s lack of chemical bonding sites can be modified by surface treatments that generate free radicals, such as with corrosive chemicals (e.g. acrylic acid) or by ionic bombardment with plasma treatments. The broken molecular bonds produce more polar sites, thus providing increased surface wettability and reactivity. 

Both thermoplastics and thermosets can be used in four of the five major application areas plastics, elastomers, coatings, and adhesives. But, only thermoplastics can be used in making fibers. During the spinning and drawing process of fiber processing, it s necessary to orient the molecules. Only unbranched, linear polymers (not thermosets) are capable of orientation. 

The process of fiber spinning, described in Chapter 3 and schematically represented in Fig. 6.18, will be modeled in this section using first a Newtonian model followed by a shear thinning model. To simplify the analysis, it is customary to set the origin of the coordinate system at the location of largest diameter of the extrudate. Since the distance from the spinnerette to the point of largest swell is very small, only a few die diameters, this simplification will not introduce large problems in the solution. 

Kissa, E., Handbook of Fiber Science and Technology, Vol. II, Chemical Processing of Fibers and Fabrics, Functional Finishes, Part B (Lewin, M. and Sello, S. B., Eds.), Marcel Dekker, New York, Chapters 2 and 3 (1984). 

I Btersen, H. A.. Cross-linking with formaldehyde-containing reactants, in Handhook of Fiber Sciente and Technology. Vol. 2 Chemical processing of fibers and fabrics.- Functional Finishes, Part A, Lewin, M. and Sello,... 

DOW CORNING FF-400 and DOW CORNING 193 fiber finish additives are silicone-ethylene oxide copolymers that exhibit useful characteristics in the manufacture and processing of fibers and yarns. Some of these characteristics include lubricity, heat stability and static control. 

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