| Abstract: | The dependence of shear degradation of polymer solutions on capillary length at constant shear stress is investigated with solutions of poly(isobutylene) (Mvis=6,1 · 106) in toluene. We examined concentrations of 0.1, 0.25, 1 and 4% and found the degradation to increase with capillary length. In 0,1% solution we found a decreased efficiency of degradation, due to a change in the structure of solution. Flow instabilities, which appear above a critical shear rate D in polymer solutions and pretend a loss in viscosity, are not caused by shear degradation. This result supports our interpretation of unstable flow of polymer solutions as slip flow (spurt). |
