Diagnostics of Apparent Wall Slip in Aqueous Polymer Solutions

Abstract

Articles you may be interested inSliding plate rheometer studies of concentrated polystyrene solutions: Nonlinear viscoelasticity and wall slip of two high molecular weight polymers in tricresyl phosphate Abstract. Two experimental methods, apparent-wall-slip (AWS) rotational viscometry with "Morse-taper" sensors and electrodiffusion (ED) flow diagnostics with auto-calibrated friction probes, are used to study velocity profiles in aqueous solutions of high-molecular polysaccharides. By comparing the velocity data from the both methods, estimates are obtained of depleted layer thickness in dependence on wall shear stress. Keywords: Apparent wall slip (AWS), Electrodiffusion diagnostics (ED) of flow, Depleted layer thickness. PACS: 83.50.RpFIGURE 10. Edge effects on transient currents. Transient currents at given flow display strong deviations from DLA theory at low H (small probes). RESULTSThe ED transients for each sample were measured at given N J simultaneously for the all 4 pairs of ED probes. The resulting {D, k L } data are converted according to Eq. 5 onto the points on velocity profile v(z) inside the diffusion layer and compared with the linear AWS extrapolation,