Processing, thermoplastics fiber spinning

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. 

Recent researches in life cycle assessments (LCA) have also focused to enable PLA to find its place among traditional commodity polymers for many applications in the agricultural sector as well as in the packaging field (the food and nonfood sector). It was found that PLA can be processed like all other thermoplastic polymers with extrusion, injection molding, blow molding, thermoforming or fiber spinning processes into various products. 

PBS is a typical thermoplastic and can be processed via various methods, such as extrusion, injection molding, film blowing, fiber spinning, and thermoforming. It has been reported that PBS can be processed into melt-blown, multifilament, monofilament, nonwoven, flat and split yarn, injection-molded products, film, paper laminate, sheet, and tape for applications in the textile and plastic industries. 

It is generally known that melt shear viscosity is a material property useful for evaluating melt processability of the material in traditional thermoplastic processes such as injection molding or extrusion. For conventional fiber spinning thermoplastics such as... 

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. 

Thermoplastic fibers are typically fabricated via a melt spinning process wherein the melt is extruded through the many holes in a spinneret and cooled to harden. Other fiber materials can be dissolved in a solvent and then exhuded, with the sohd fibers precipitating from solution either due to a chemical reaction in a liquid bath or due to solvent evaporation in a gas. The latter method, dry spinning, is closest to the focus of this section— electro spinning of nanoflbers. 

The melt-spinning process used to convert mesophase pitch into fiber form is similar to that employed for many thermoplastic polymers. Normally, an extruder melts the pitch and pumps it into the spin pack. Typically, the molten pitch is filtered before being extruded through a multi-holed spinnerette. The pitch is subjected to high extensional and shear stresses as it approaches and flows through the spinnerette capillaries. The associated torques tend to orient the liquid crystalline pitch in a regular transverse pattern. Upon emerging from the... 

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