The non-uniform phase structure in blend fiber. I. Non-uniform deformation of the dispersed phase in melt spinning

By melt spinning of incompatible polymer blends, the deformation of the dispersed phase was investigated in the fiber spinning process, for polypropylene/polystyrene (PP/PS) blend fiber and low density polyethylene/polyamide 6 (LDPE/PA6) blend fiber, respectively. Two kinds of the take-up fiber all exhibit the matrix fibrillar morphology, but with the opposite morphology. For PP/PS take-up fiber, the dispersed PS fibrils were finer in the core than near the surface. On the contrary, the dispersed PA6 fibrils were finer near the surface than in the core for LDPE/PA6 take-up fiber. However, for the special fiber in which the extensional flow was absent, there was the uniform morphology in either PP/PS or LDPE/PA6. Thus, fibrils’ non-uniform deformation, occurred in the drawing process, was considered to be due to the radial non-uniform processing conditions across the spin-line cross-section. The distribution of fibrils’ diameter was also investigated on the whole cross section. Rheological properties of each component were measured by the capillary rheometer. The non-uniform phase structure in blend fiber is a new phenomenon in the extensional flow.