Effects of entanglement and dispersity on shear strain hardening

Polystyrene solutions are the widely used model system to study polymer dynamics and rheology. In the strong nonlinear region, we shear polystyrene solutions of uniform or bimodal distribution up to unprecedented high rates. The unique shear strain hardening takes place on such solutions with high Tg solute, irrespective of dis-persity. Non-Gaussian stretching of chains is suggested by full recovery even after a shear strain of 60. Shear strain hardening in uniform solutions happens at a universal Rouse-Weissenberg number, 150, regardless of the number of entanglements. The critical stress between traditional stress overshoot and hardening is around 104 Pa, for 10% solutions regardless of dispersity or number of entanglements. This systematic study charts the parameters for shear strain hardening.

Automated summary

Polystyrene solutions are widely used as a model system to study polymer dynamics and rheology. This study explores the shear strain hardening behavior of polystyrene solutions under high shear rates, regardless of the distribution. The findings suggest non-Gaussian stretching of chains and identify some key parameters for shear strain hardening.