SIMULATION OF THE ORIENTATION AND ITS DISTRIBUTION ACROSS A FILAMENT USING THE STEADY-STATE SINGLE FILAMENT MELT SPINNIG THEORY

Numerical calculation of the theoretical equations for melt spinning was conducted under the steady state condition. Calculated results were related to the structural and mechanical properties of as-spun yarn. It was found possible to estimate the yarn properties easily by the computer simulation. The calculation shows; 1. The observed birefringence of poly(ethylene terephthalate) (PET) fiber is related to the computed spinning stress, viz., stress value at the point where the ratio of the yarn running velocity to take-up speed is 0.95. 2. In high speed melt spinning, the average degree of orientation of a filament is determined mostly by the take-up speed. 3. The orientation distribution across a filament becomes larger with the increase of the spinning speed, which may be caused by the increased temperature gradient across a filament. 4. To decrease the orientation distribution, increase in the cooling air temperature during the melt spinning process is effective. Experiments of PET melt spinning showed good agreements with the above-mentioned expectations.