Shear stress relaxation in linear polystyrene solutions after a stepwise decrease of shear rate from a value of γ1 to a lower value γ2was observed with an R-17 Weissenberg rheogoniometer. The experimental results in the region of low shear rates agreed well with the theory of linear viscoelasticity. In nonlinear regions, it was found that the initial parts of the relative relaxation curves compose a single line independent of γ2 if γ1is kept constant. The behavior is consistent with that of stress development after a stepwise increase of shear rate, reported previously. It was concluded that the quasi-network structure of polymer solutions has a stability and the structure change occurs with a time lag.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry