title: High resolution shear profile measurements in entangled polymers.
abstract: We use confocal microscopy and particle image velocimetry to visualize motion of 250-300 nm. fluorescent tracer particles in entangled polymers subject to a rectilinear shear flow. Our results show linear velocity profiles in polymer solutions spanning a wide range of molecular weights and number of entanglements (8< or =Z< or =56), but reveal large differences between the imposed and measured shear rates. These findings disagree with recent reports that shear banding is a characteristic flow response of entangled polymers, and instead point to interfacial slip as an important source of strain loss.
authors.affiliation: School of Chemical & Biomolecular Engineering, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Keesha A
authors.initials: KA
authors.lastname: Hayes
authors.forename: Mark R
authors.initials: MR
authors.lastname: Buckley
authors.forename: Itai
authors.initials: I
authors.lastname: Cohen
authors.forename: Lynden A
authors.initials: LA
authors.lastname: Archer