| Abstract: | The time dependence of shear and normal stresses during constant shearing of some polystyrene and poly(ethylene oxide) solutions in Aroclor 1248 was measured by means of a Weissenberg rheogoniometer. The stresses of the poly(ethylene oxide) solutions first increase rapidly with the increase of strain, then decrease to a value lower than the value in the stationary state, pass another maximum smaller than the first one, and finally reach a steady value. At the end of the shearing of these solutions at high shear rates, the formation of aggregates was clearly evident. The polystyrene solutions became time-dependent only after a certain shear rate and then showed a rheopectic behavior. The difference in behavior is explained qualitatively by the differing tendencies of these polymer chains to form a network. |
