Relation between molecular orientation and mechanical properties in differently processed polyamide 4.6/6 textile yarns

A series of Polyamide 4.6/6 textile fibers spun according to different technologies, high-speed spinning, and the spin drawing, was investigated by C-13-NMR, ultrasonic, optical, WAXS, and DSC measurements. It was shown from the determination of the chain orientational order parameters and the DSC results that in the as-spun textile fibers two different crystallization modes occur, i.e., up to spinning speeds of 3500 m/min spherulites and orientationally ordered crystallites are present at the same time. With increasing fiber spinning speeds, the orientationally ordered crystallites grow at the expense of the spherulitic structures. At spinning speeds beyond 3500 m/min the spherulites vanish completely and only the orientationally ordered crystallites are observable and the tenacity increases. The drawn fibers only show a fibril-like structure and spherulites do not occur. Accordingly the drawn fibers have a higher level of tenacity. (C) 1997 John Wiley & Sons, Inc.