(161x) The Flow of Entangled Polymers Under High-Stress Shear in Capillary Extrusion

Capillary extrusion has been frequently applied to study the flow behavior of highly entangled polymer melts, where the stick-slip and gross melt fracture typically emerge when the applied stress is approaching the plateau modulus, G_pl, of the polymer. Here, we show that the stick-slip and the gross melt fracture can be strongly suppressed and eliminated by properly choosing entangled polymer melts and lowering the testing temperatures. Consequently, we were able to access the flow of highly entangled polymer melts at applied stresses larger than the G_pl as evidenced by the smooth surface of the extrudates. We found two new flow regions in addition to the terminal flow and the shear thinning regions that are typically observed in the capillary extrusion of entangled polymers. We will present the characteristics of the new flow regions in this work and our observations offer clear descriptions of the features of various flow regions of entangled polymers up to high-stress shear.