Fibers process volume

Whether or not it is obtained depends on the washing mechanism allowing the shrinkage, and hence the crimp, to develop prior to the completion of regeneration. Crimp development only occurs fiiUy in staple fiber processes where the sluicing operation allows the cut tufts of acid tow to expand freely in ample volumes of hot Hquor. 

Pyrolysis must be carried out with careful control of atmospheric conditions. The gases formed during pyrolysis cause the fibers to undergo a weight loss of 20-40% (60-80% volume decrease), and the fibers achieve a final diameter of 10-15 (xm. This diameter is desirable for many ceramic and plastic composite applications. A more complete discussion of this fiber processing has been presented recently (20). 

E. S. Olson, Wet Processing, Volume I, Preparation of Fibers and Fabrics, Noyes, Park Ridge,... 

Note that in the assessment of the effective process volume it has been considered only a surface layer 0.5 mm thick because it is only that surface layer that takes place in the high cycle fatigue process. The beam under consideration has a much larger process volume. The bending stress reaches its maximum at the fix end on the farthest fibers from the neutral axis. The 90 % of the maximum stress criterion is adopted (see Sect. 7.5) to evaluate the process volimie. Stresses maintain equal or larger than 90 % of the maximum value within a distance d from the surface equal to... 

Carbon—carbon composites for rocket nozzles or exit cones are usually made by weaving a 3D preform composed of radial, axial, and circumferential carbon or graphite fibers to near net shape, followed by densification to high densities. Because of the high relative volume cost of the process, looms have been designed for semiautomatic fabrication of parts, taking advantage of selective reinforcement placement for optimum thermal performance. 

Slit-Film Fiber. A substantial volume of olefin fiber is produced by slit-film or film-to-fiber technology (29). For producing filaments with high linear density, above 0.7 tex (6.6 den), the production economics ate more favorable than monofilament spinning (29). The fibers are used primarily for carpet backing and rope or cordage appHcations. The processes used to make slit-film fibers are versatile and economical. 

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