HIGH SPEED MELT SPINNING OF POLYESTER FILAMENTS: EFFECT OF SPINNING VELOCITY ON THE PROPERTIES AND MOLECULAR ORIENTATION

An experimental equipment for high speed spinning for the spinning velocity up to 10, 000m/min has been developed. With this new equipment, it is possible to spin continuously polyester fibers (intrinsic viscosity: 0.64, melt temperature: 293°C) within the velocity range of 1, 000_??_7, 500m/min. In this paper, the properties and the molecular orientation of the polyester fibers spun by using this equipment are investigated as a function of spinning velocity. The results are as follows: 1. The birefringence, which is a measure of molecular orientation, increases in proportion to the spinning velocity within the range of 1, 000_??_7, 000m/min. With the velocities above 4, 000m/min, the increase in birefringence is due to not only the molecular orientation but also the crystallization and the crystalline orientation. 2. The representative properties of the high speed spun filaments within the range of 6, 000_??_7, 000m/min are characterized by the physical values as follows; a) Melting point: 262_??_268°C b) Crystalline orientation for c-axis: 0.91_??_0.93 c) Crystallinities obtained by densities: 39_??_44% d) Initial Young's modulus: 81g/D