二段階ずり速度変化法による高分子溶液の非定常粘度

抄録

Transient shear stresses in linear polystyrene solutions after stepwise change of shear rate from a steady shear rate γ₁ to a higher or a lower values of γ₂ were observed using a Weissenberg rheogoniometer type R-17. The initial parts of stress development curves after stepwise increase of shear rate from constant γ₂ to different γ₁ compose a single line independent of γ₂. The initial parts of stress relaxation curves relative to the first steady state also compose a single line independent of γ₂ if γ₂ is kept constant. It was concluded that the original quasi-network structure of polymer solutions have a stability and in the case of stepwise increase of shear rate the original structure is ruptured when a certain critical strain is accumulated in the solution. It was also concluded that the initial slopes become lower with increasing γ₁ reflecting decrease of the effective entanglement density with increasing γ₁.