DOG-LEGGING IN THE MELT-SPINNING PROCESS

Experiments were performed in a continuous capillary rheometry to inve stigate the dog-legging mechanism in a melt spinning process. The bend ing angle of the spinline was measured under various spinning conditio ns while spinning PP, PET, and PEN fibers. Experimental results indica te that obstacles inside the capillary of the spinnerette are the prim ary cause of bending of the spinline. The bending angle is greatly inf luenced by the obstacle's dimensions and position inside the capillary . An increase in the obstacle's radius or a decrease in the obstacle's length caused the bending angle to increase. The closer the obstacle was to the exit of the capillary implied the bending angle would be th e wider except for the block immediately above the exit. Also at high shear rates, PEN was found to be relatively insensitive to spinline-be nding than PET polymers. Ln accounting for the dog-legging behavior, o ur results suggest that the die swell model is more realistic than the conventional vortex model.