Extensional Viscosity of Polystyrene Solutions in Dilute Region

抄録

Extensional viscosities η_e(ε) of polystyrenes (PS) with high molecular weights in benzyl butyl phthalate (BBP; a good solvent for PS) and dioctyl phthalate (DOP; a θ solvent for PS) were studied in the dilute region for viscosity as a function of the extensional rate with an opposing jets extensional rheometer.
The η_e(ε) data obtained with use of different orifice geometries agree with each other within experimental errors. The extensional viscosity at low ε limit, η_e⁰ is about three times larger than the corresponding zero-shear viscosity in accordance with Trouton's rule.
In high ε region, the extensional-thickening was observed for all the solutions. The critical extensional rate ε^* at which the η_e(ε) deviates from η_e⁰ is confirmed to be related to the longest relaxation time of the solutions.