EXPERIMENTAL AND THEORETICAL-STUDY OF RECTANGULAR FIBER MELT-SPINNING

In order to study the process of rectangular fiber melt spinning, expe rimental and theoretical investigations are conducted. Several differe nt values of such process variables as die dimension, flow rate, take- up speed, quench air speed and temperature, and die temperature are ch osen for manufacturing poly(ethylene terephthalate) fibers. Both 1- an d 2-dimensional formulations are employed under the Newtonian fluid as sumption. Two separate mathematical schemes are then combined via the Picard iteration to provide a convenient tool estimating the process w ith all variables taken into account and with as little computational effort as possible. From this experiment, it is found that the extruda te exhibits negative swelling in the fiber width direction, which resu lts from the negative second normal stress direction in shear flow ins ide the die. Fiber cross-section takes elliptical shape at the point o f maximum thickness swell and then gets flat as it approaches that tak e-up point. As to numerical simulation, all the quantities such as fib er dimension, velocity, temperature and tension except variables relat ed to cross-sectional are are relatively well described by this simple theory. Neglect of material elasticity and over-simplification of tem perature variation along fiber cross-section are main causes for the d eviation of calculated values from experimental data.