Shear Thickening in Dilute Polymer Solutions: Transient Analysis

Transient shear properties of dilute polymer solutions are investigated in the shear rate regions where shear thickening can occur. Comparison of transient rheological and optical data with the two coupled Maxwell modes model offers insight into the physical mechanisms that give rise to this anomalous behavior. Specifically, shear thickening occurs due to the deterioration of the size and anisotropy of structures deformed at lower shear rates. Coincident theoretical and experimental discontinuities in the transient profiles of the dichroic orientation angle appear to confirm the prior statement.