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 investig ated by C-13-NMR, ultrasonic, optical, WAXS, and DSC measurements. It was shown from the determination of the chain orientational order para meters and the DSC results that in the as-spun textile fibers two diff erent crystallization modes occur, i.e., up to spinning speeds of 3500 m/min spherulites and orientationally ordered crystallites are presen t at the same time. With increasing fiber spinning speeds, the orienta tionally ordered crystallites grow at the expense of the spherulitic s tructures. At spinning speeds beyond 3500 m/min the spherulites vanish completely and only the orientationally ordered crystallites are obse rvable and the tenacity increases. The drawn fibers only show a fibril -like structure and spherulites do not occur. Accordingly the drawn fi bers have a higher level of tenacity. (C) 1997 John Wiley & Sons, Inc.