Measurement of Filament Temperature and Analysis of Orientation-induced Crystallization Behavior in High-Speed Melt Spinning Process

Abstract

The measurement of the filament temperature along a spinline in a high speed melt spinning process provides information on the cooling behavior and crystallization behavior of running filament. The filament temperature was analyzed through simultaneous measurements of infrared radiation intensity and the diameter of the filament. The determined empirical formula for the evaluation of the cooling of the running filament predicts a slower cooling rate than that obtained from the Kase and Matsuo equation. The diameter profile for a poly (ethylene terephthalate) spinline at a take-up velocity of 6km/min showed a so-called neck-like deformation at 140-150cm down from the spinneret, and the temperature profile showed a maximum just after the end of the deformation. This temperature increment reflects the heat of crystallization induced by molecular orientation. The rate of crystallization in the spinline, which is estimated from the temperature and diameter profiles, at a temperature of ca. 160°C and birefringence of 0.108 is 105 times greater than that of the isotropic state. It is suggested that crystallization proceeds rapidly just after the end of the neck-like deformation in a high speed spinning process.