title: Apparent fracture in polymeric fluids under step shear.
abstract: Recent step strain experiments in well-entangled polymeric liquids demonstrated a bulk fracturelike phenomenon. We study this instability by using a modern version of the Doi-Edwards theory for entangled polymers, and we find close quantitative agreement with the experiments. The phenomenon occurs because the viscoelastic liquid is sheared into a rubbery state that possesses an elastic constitutive instability [G. Marrucci and N. Grizzuti, J. Rheol. 27, 433 (1983)]. The fracture is a transient manifestation of this instability, which relies on the amplification of spatially inhomogeneous fluctuations. This mechanism differs from the fracture in glassy materials and dense suspensions.
authors.affiliation: Soft Matter Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom.
authors.forename: Okpeafoh S
authors.initials: OS
authors.lastname: Agimelen
authors.affiliation: Soft Matter Physics Group, School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Olmsted