Abstract
Filaments of isotactic polypropylene and high density polyethylene have been produced by melt spinning in the presence of torsional shear, which is achieved by an air-jet false twister. The twister can rotate by air vortex the running filament without any contact and give the filament set-twist before coming the point of complete solidification of the threadline.
The twist number is increased as the applied air pressure to the twister is increased and it reaches the maximum value at the take-up velocity near to 250m/min. The maximum twist number is discussed as a result of the interrelation between the filament diameter and the speed of running filament. The set-twist number is also discussed from the standpoint of false twist mechanism under various spinning conditions.
Molten polymer filaments are affected by elongational and torsional strains along the spinning line and thus the physical properties of the spun twisted filaments are similar to those of the filaments spun at higher take-up velocities without torsional shear.
