Broad Shear Range Viscometry of High Polymer Solutions: Polystyrene and Polyisobutene in Decalin

The flow behavior at 25°C for decalin solutions of polystyrenes (PS) of molecular weights up to $7×106$ and polyisobutenes (PIB) of molecular weights up to $3×106$ was examined over a wide range of shear rate up to about $105 sec−1$ for several polymer concentrations. Measurements involved conventional glass capillary viscometers, a Rheometrics Mechanical Spectrometer, and custom‐built high‐shear concentric cylinder viscometer. Low‐shear Newtonian viscosities for the higher concentration entanglement region follow the forms $η0=CM0.57$ for PS and $η0=CM0.68$ for PIB. Gel permeation chromatography was used to determine polymer molecular weight, its distribution, and possible change on shearing. Shear degradation was observed for polymers at high values of concentration, molecular weight, and shear stress.