抄録
Poly (ethylene terephthalate) (PET) containing 0.1 wt% sodium stearate (SS) and plain PET were melt spun at take-up velocities from 1 to 7km/min, and effect of the nucleating additive on the fiber structure formation in high-speed melt spinning process was investigated. When take-up velocity was lower than 4km/min, SS had no influence on the structure of the spun filaments. Orientation-induced crystallization was observed at take-up velocities above 5km/min, and PET filaments with SS showed higher birefringence and lower density than plain PET filaments. By incorporating SS in PET the position of neck-like deformation in spinline moved downward, although the filament diameter profiles from the spinneret up to the neck-like deformation point were almost the same between the two polymers. Spinline stress at the take-up position was higher for plain PET than that for PET with SS. However, spinline stress at a position just below the neck-like deformation was higher for PET with SS, owing to the component of air drag force. From this it is considered that a higher birefringence for PET filaments with SS is due to a higher spinline stress at the neck-like deformation point. The fact that the PET filaments with SS show a lower density can be thought to be due to the decrease in crystallization temperature caused by the downward movement of the position of neck-like deformation.
