UNIQUE CRYSTALLINE-STRUCTURE AND PERFORMANCE OF POLY(ETHYLENE-TEREPHTHALATE) MELT-SPUN FIBERS

Modification of the threadline dynamics has effected significant alter nations in the structure and improvements in the properties of high-sp eed melt spun poly(ethylene terephthalate) (PET) fibers. Key process p arameters extant in the threadline dynamics, such as temperature, tens ile stress, and deformation time, were independently controlled throug h proper implementation of on-line perturbations. The placement of a l iquid isothermal bath in close proximity to the spinneret in the melt spinning threadline provided tremendous increase in the spinning stres s while at the same time controlled the filament temperature correspon ding to development of the desired fiber structure. Characterization o f the fiber structure and physical properties has been carried out usi ng birefringence measurements, density, shrinkage, x-ray diffraction, DSC, FTIR spectroscopy, and tensile tests. The results provided suffic ient evidence to support the existence of a unique crystalline morphol ogy that led to the significantly improved tensile properties and exce llent dimensional stability of the resulting fibers. This unique cryst alline morphology was typically characterized by the presence of a lar ger amount of extended chain segments and an enhanced molecular connec tivity. (C) 1995 John Wiley and Sons, Inc.