The production rate of polymer fibers by extrusion is usually limited by the appearance of a series of instabilities ("melt fracture") that lead to unwanted undulations of the surface. We present... Show moreThe production rate of polymer fibers by extrusion is usually limited by the appearance of a series of instabilities ("melt fracture") that lead to unwanted undulations of the surface. We present both qualitative and quantitative experimental evidence that-in addition to previously known polymer-specific scenarios-there is an intrinsic route towards melt fracture type phenomena: a nonlinear ("subcritical") instability of viscoelastic Poiseuille flow. Show less
