Shear and normal stress developments after stepwise increases of shear rate from a steady shear rate γ1to a higher one γ2 were observed with a Weissenberg rheogoniometer Type R-17 in linear polystyrene solutions. The initial parts of the stress-development curves at different γ2 compose a single line if γ1is kept constant, and the initial slope becomes lower with increasing γ 1 It was concluded that the original quasi-network structure of polymer solutions remains unchanged until a certain critical strain is accumulated in the solution. The difference in the initial slope at different γ1 may be caused by a change in the effective entanglement density with γ. It is also pointed out that the additivity of responses in viscoelastic behavior of polymer solutions does not hold in nonlinear regions.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry