THEORETICAL CONSIDERATION OF AIR GAP EFFECT ON FIBER FORMATION DURING WATER-QUENCHED MELT SPINNING AND APPLICATION OF AIR GAP SPINNING TO CHARACTERIZATION OF FLUID RELAXATION TIME

Theoretical studies on the dynamics of water-quenched air gap melt spinning for poly(ethylene terephthalate) (PET) were done. Spinning tension in the air region increases rapidly with decreasing air gap length. Especially, in the case of air gap length less than 2 cm, high spinning tension can be obtained. It might be thought that high spinning tension during spinning process leads to high molecular orientation of super fibers such as Aramid fibers. Maximum deformation rate in the spinning process having narrow air gap appears at the interface of air and water, which is also related to high molecular orientation. Using air gap spinning, draw resonance experiments were performed to characterize the relaxation time of PET. Comparing the experimentally obtained draw resonance wave forms with those of computations for Maxwell fluid model, the relaxation time is estimated to be about 0.002 s. This value almost coincides with that obtained by other methods.