Rheological and theoretical estimation of the spinnability of polyolefines- Part I: Rheological study

Melt spinning is a polymer processing technique that makes great demands on the extensibility of the polymer melt in the distance between die exit and solidification point [1]. The polymer material is exposed to a rapidly gro wing deformation rate over a large range of deformation within a short time of about 100 milliseconds. Simultaneously an extreme cooling occurs with c ooling rates of about 1000 K/s. For this reason only a few polymer material s are usable for this kind of polymer processing with sufficient take-up sp eeds. Most polymers show a fiber break in the molten state either by brittl e cohesive rupture or ductile failure when approaching critical conditions of deformation. The rheological behaviour of a polymer melt at the critical conditions of deformation in the fiber forming process can not be predicte d by means of usual rheological material functions. This paper reports the attempt to find out material functions, which describe the critical deforma tion states of the melt spinning process. The established material function s ave compared with the results of spinning experiments to estimate their p racticality.