Fiber spinning presentation

Because of the capacity to tailor select polymer properties by varying the ratio of two or more components, copolymers have found significant commercial appHcation in several product areas. In fiber-spinning, ie, with copolymers such as nylon-6 in nylon-6,6 or the reverse, where the second component is present in low (<10%) concentration, as well as in other comonomers with nylon-6,6 or nylon-6, the copolymers are often used to control the effect of sphemUtes by decreasing their number and probably their size and the rate of crystallization (190). At higher ratios, the semicrystalline polyamides become optically clear, amorphous polymers which find appHcations in packaging and barrier resins markets (191). 

The dimensionless criterion factor f = qv/a is of great importance in estimating liquid flow parameters the discussion of its values is beyond the frames of the present work (as outlined in the references cited). It may be noted, however, that the same expression appears in the equation evaluating the ability of polymers for thread and fiber spinning 15>. To the first approximation, the criterion f = qv/o may be treated as a measure of shape-keeping ability of liquid in flow. 

In past studies (3), Electron Spin Resonance, ESR, has been used to investigate bond rupture associated with stress-ozone degradation in unsaturated rubbers. It was believed that it might be enlightening to perform similar experiments on plastics ( 5, 8, 10, 11). In the study reported here the combined effects of environment (O3, N02 and S02) and sustained stress on the ultimate properties of Nylon 6 fibers are presented. These agents were found to have a profound effect on strength, toughness and the deformation-bond rupture kinetics. 

A. Ziabicki, The Role of Phase and Structural Transitions in Fiber Spinning Processes, presented at Society of Fiber Science and Technology, Japan, 25th Anniversary, Tokyo-Osaka (1969). 

Any amylopectin present is tolerated as an impurity that adversely affects the fiber spinning process and the strength of the final product. Since natural starch is rich in amylopectin, pre-treating of natural starch is done to obtain the amylose-rich portion which is highly desirable for fiber spinning (1). 

For the above polymers, DuPont launched the commercial production of high-strength and high-modulus Kevlar libers and the Akzo Nobel corporation began production of Twaron libers. In the former, USSR scientists from the Fiber Research Instimte (Khimvolokno) synthesized high-modulus Terlon and Vmivlon fibers by fiber spinning from lyotropic solutions of aromatic copolyamides. Some mechanical properties of aromatic amides produced by different companies are presented in Table 4. °... 

The use of mixed solvents is widespread, because it offers the possibility to tailor desirable thermodynamic conditions by mixing two liquids with sufficiently different qualities in adequate ratios, instead of the often inconvenient or even impossible variation of temperature. The combination of good solvents with precipitants is the basis of many industrial processes, like membrane production or fiber spinning. In order not to go beyond the scope of the present contribution, the following considerations are limited to complete miscibility of the components of the mixed solvent. There is, however, no particular difficulty to extend the treatment to incompletely miscible components of mixed solvents. 

The activity level to develop new polymers for fiber spinning is at an all-time high. This seems incompatible with the present low selling price of polyester and polypropylene, but many major chemical companies continue to look for polymers for special niche markets. Among these polymers are... 

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