Origin of Shear Thinning in Unentangled Polystyrene Melts
Giovanni Ianniruberto, G. Marrucci
Abstract
Nonlinear shear data of an unentangled polystyrene melt [Santangelo, P. G.; J. Rheol. 2001, 45(2), 583−594] are compared to Brownian dynamics predictions of Fraenkel chains. All parameters needed to perform the comparison are obtained from the known molar mass, zero-shear viscosity, and from older data for the linear glassy contribution [Inoue, T.; Macromolecules 1991, 24(20), 5670−5675]. Comparison reveals that the magnitude of shear thinning of the unentangled melt cannot be explained unless account is taken of the flow-induced reduction of the monomeric (Kuhn segment) friction coefficient.
Topics & Concepts
Shear thinningMolar massPolystyreneShear (geology)ViscosityMaterials scienceBrownian dynamicsThermodynamicsThinningShear flowBrownian motionMonomerPolymer chemistryPolymerComposite materialMathematicsPhysicsBiologyEcologyStatisticsRheology and Fluid Dynamics StudiesMaterial Dynamics and PropertiesPolymer crystallization and properties