The non-uniform phase structure in blend fiber. II. The migration phenomenon in melt spinning

Abstract

The migration phenomenon was investigated in polypropylene/polystyrene (PP/PS) blend fiber and low density polyethylene/polyamide 6 (LDPE/PA6) blend fiber. The migration of fibrils in melt spinning was evaluated by the variation of fibrils’ area ratio over the cross section of blend fiber. In PP/PS blend fiber, the dispersed PS deformed into many highly oriented fibrils in the PP matrix, and PS fibrils migrated towards the surface of the take-up fiber in the fiber spinning process. On the contrary, PA6 fibrils migrated into the core of the take-up fiber, while the dispersed PA6 deformed into many highly oriented fibrils in the LDPE matrix for LDPE/PA6 blend fiber. Otherwise, no migration phenomenon was observed in the special fiber that was prepared without any drawing, neither in PP/PS nor in LDPE/PA6. Therefore, in the fiber spinning process, the migration phenomenon actually occurred mainly in the drawing process, which is the non-isothermal uniaxial extensional flow. Comparing with migration mechanisms in the shear flow, the migration phenomenon in melt spinning was probably due to the radial non-uniform extensional stress, the extensional viscosity.