Effect of Processing History on Flow‐Induced Crystallization of Polyethylene With Long‐Chain Branches

ABSTRACT The effect of applied processing history on rheological properties and flow‐induced crystallization is studied in polyethylene with long‐chain branches that is prepared using a metallocene catalyst. The sample processed by a two‐roll mill, in which elongational flow is dominant, shows marked strain hardening in transient elongational viscosity, as well as prompt crystallization once shear flow is further applied. In contrast, strain hardening in transient elongational viscosity and shear‐induced crystallization are not prominent after passing through a single‐screw extruder. These results suggest that shear‐dominant flow in the extruder weakens the role of long‐chain branches on rheological properties, known as shear modification, and flow‐induced crystallization.