STRUCTURE AND PROPERTIES IN ULTRA-HIGH SPEED SPINNING OF POLY (BUTYLENE TEREPHTHALATE)

Abstract

Ultra-high speed spinning of poly (butylene terephthalate) (PBT) has been carried out for take-up velocity up to 14, 000m/min. The structure and properties of as-spun fibers were investigated and compared with poly (ethylene terephthalate) (PET).
Orientation of molecules and crystallization proceed largely at relatively low velocities up to 3, 000m/min. Increase in birefringence becomes small above 3, 000m/min, and the skin-core structure developes above 10, 000m/min, though the core part is small in comparison with PET. Density and maximum birefringence in the cross section of the fiber increase up to 14, 000 m/min. SAXS shows a typical meridian reflection and a weak equatorial streak at ultra-high take-up velocities, which suggests the regular arrangement of crystallites perpendicular to the fiber axis. Generation of microvoids in PBT fiber is not so remarkable in comparison with PET fiber. The size of crystallites and the amount of the α crystal form increase with increasing take-up velocity, Melting temperature rises about 21°C in the range of take-up velocity from 1, 000 to 14, 000m/min.
As PBT has more flexible chains, crystallization of the polymer occurs more easily along spinline than that of PET. This may explain that the more stable fine structure appeares in the ultra-high take-up velocities.