Fiber spinning spinnability

By contrast, other polymers such as polyolefins and PVA form immiscible blends with HKL. In fact, phase separation is observed in fibers produced from the thermal spinning of HKL and PP. The fiber spinning properties of several PP samples having various melt viscosities and tacticities were examined. Most of the HKL/PP blends show poor or bad fiber spinnability. However, excellent fiber spinning was achieved with PP samples having a thermal viscosity comparable to the HKL. 

During fiber-spinning and film-blowing, one may expect the extensional viscosity increases with the increase of dv/dr. As the local increase of dv/dx leads to the reduction of the fiber diameter, the increase of viscosity could prevent further thinning and thus makes the fiber more homogeneous in thickness and stronger. Such a performance of polymer fluids has been described as spinnability (Petrie 2006). 

An important basis of all fiber-spinning operations is degree of spinnability... 

The spinnability and spinning properties of a polymer are of the highest importance in the manufacturing of staple fibers and filaments. There are many analogies to the production of films, where breaks or splits are concerned. The frequency of yarn breaks determines the economic viability of the production process, as well as the competitiveness and the reputation of the manufacturer. Today, in the age of automation, it would be theoretically possible to manage the processing of the polymer with a minimum of staff if no yam breaks disturbed the processing. 

Fibers of aluminum nitride have been produced by the melt-spinning of ethyl-alazanes derived from the reactions of triethylaluminum and ammonia.72 The spinnable products have compositions such as (I l AIN11 )c(Et2A INH2 )v(Et3 A1 ),] which probably consist of linked alazane rings and chain structures. Pyrolysis in ammonia gives aluminum nitride fibers. 

Summary The heterogeneous catalytic redistribution reaction of methylchlorodisilanes provides spinnable poly(methylchlorosilanes/-carbosilanes). Especially copolymers like poly(methylchlorosilanes-co-styrenes) are suitable polymers for melt spinning. The high reactivity caused by Si-Cl bonds enables oxygen free curing methods of the melt spun polymer filaments with ammonia. The synthesis is achieved without the employment of highly reactive metals and any solvents. The thus produced SiC fibers exhibit oxygen contents lower than 1 wt. %. 

As Rosenau et al. [49] indicated that paper grade pulp, unbleached chemical pulp, cotton and rayon fiber wastes, or even paper wastes can be used as raw materials for Lyocell fiber production, even though problems with spinnability may be encountered in some cases. In preparation for spinning dope, a 50-60% aqueous NMMO is used with the addition of 0.01 0.10% antioxidant to prevent cellulose degradation. A typical antioxidant is PG [50]. In a typical Lyocell industrial process, the slurry is produced from cellulose pulp and an aqueous NMMO solution. Typical compositions are 50-60% NMMO, 20 30% water, and 10-15% pulp [48]. Subsequently excess water is efficiently evaporated at temperatures lower than 150°C and... 

The material discussed up to this point has been intended to give the reader an understanding of how the majority of acrylic fibers are manufactured. In this section, we discuss some of the less conventional spinning processes that could be used to produce fibers for special applications. We also include a section on optimization of spinnability in which some of the more fundamental aspects of the rheological behavior of the fiber in the spin bath are discussed. Completing this section is a discussion of the dyeing of acrylic fibers. 

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