Generate extensional flows in microchannels and quantify the extensional viscosity of dilute polymer solutions.
Shear rheometry alone is inadequate to describe polymer behavior in most types of flow fields. In fact, elongational flows are an important component of polymer processing, such as in fiber spinning, injection molding and film blowing. Although there are few techniques that allow for the measurement of the extensional behavior of mobile fluids, most of the methods available are restricted to low strain rates and high viscosity fluids.
The method involves using hyperbolic contractions at a microscale level, which allows for higher strain rates to be achieved.