Fiber spinning techniques

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). 

Nanocomposite conventional mesoscale fibers (textile fibers that carry nanoparticulate filler) are produced via conventional fiber-spinning techniques by incorporating well-dispersed nanoparticles into the spinning dope. For instance, an intercalated poly(ethylene terephthalate) (PET)/organo-montmorillonite (MMT) nanocomposite prepared by in situ polymerization of the polyester in the presence of MMT clay was successfully melt spun into microfibers (Guan, G.-H., et al. 2005). Melt-spun conventional fibers of... 

There are many ways to implement nano-scale controlled properties into textiles. One is to give the fiber itself a nano-scale by fiber spinning. With novel fiber spinning technologies it is possible to spin fibers with diameters between 20 and 500 nm 10-500 times thinner than fibers spiimable by traditional fiber spinning techniques. An aim is to make the production of fibers with diameters below lOOnm highly productive and state-of-the-art. 

In the event the devices for measuring are not available, there are two methods for obtaining approximate values of The first method is based on the fiber spinning technique as shown in Figure 3.26. (The device is known as the Rheotens.) Without any discussion of the theory the extension rate is given by... 

The spinnerets in a production line assembly consist of multiple groupings of orifices thus the number of fibers from a single spinning ceU can vary. AU three spinning techniques mentioned above commonly employ spinning lines that carry as many as 250 fibers (sometimes referred to as a rope) drawn from a single multiorifice spinneret. 

Improvements in melt spinning techniques and film filament processes have made polypropylene accessible for fiber production. Low-cost fibers made from polypropylene are replacing those made from sisal and jute. 

Reservoir or coaxial fibers can be produced from the glycolide/ lactide polymers (53,55). Two different methods have been investigated. Dunn (53) utilized a melt-spinning technique in which the drug was introduced during the spinning process as a suspension or solution in a suitable lumen fluid. Eenink (55) developed a dry-... 

FIGURE 18.3 Fiber production using the three major spinning techniques. 

The development of physical methods for texturizing proteins has significantly amplified their use in several conventional and simulated foods. The principal techniques of physical modification which have been thoroughly reviewed are thermoplastic extrusion, fiber spinning and steam texturization (3,4,5). 

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