A precision-machined cross-slot flow geometry with a shape that has been optimized by numerical simulation of the fluid kinematics is fabricated and used to measure the extensional viscosity of a dilute polymer solution. Full-field birefringence microscopy is used to monitor the evolution and growth of macromolecular anisotropy along the stagnation point streamline, and we observe the formation...

Zein, the predominant protein in corn, may be used as an alternative to various commercial plastics. Plastics produced from zein tend to be brittle, so plasticizers such as triethylene glycol (TEG) and water were used in this study to alleviate brittleness. When zein is blended with water and subjected to heat and shear in a torque rheometer, zein readily generates aggregates that produce a rap...

filament stretching extensional rheometer and capillary breakup extensional rheometer are used o measure the extensional rheology of a series of wormlike micelle solutions experiencing a niaxial elongational flow. The experiments are performed using a series of wormlike micelle olutions of both cetylpyridinium chloride and sodium salicylate NaSal in an aqueous sodium hloride solution and cetylt...

We characterize the linear viscoelastic shear properties of an aqueous wormlike micellar solution using diffusing wave spectroscopy (DWS) based tracer microrheology as well as various mechanical techniques such as rotational rheometry, oscillatory squeeze flow, and torsional resonance oscillation covering the frequency range from 10(-1) to 10(6) rad/s. Since DWS as well as mechanical oscillator...

We describe a new triborheometry fixture that can be utilized with a commercial torsional rheometer in order to explore the coupled rheological and tribological properties of complex fluids and solid-liquid systems. The fixture is self-leveling and both the normal load and the sample gap can be monitored or controlled. At large gaps, the fixture imposes an approximately constant shear rate on t...

Microfluidic devices are ideally suited for the study of complex fluids undergoing large deformation rates in the absence of inertial complications. In particular, a microfluidic contraction geometry can be utilized to characterize the material response of complex fluids in an extensionally-dominated flow, but the mixed nature of the flow kinematics makes quantitative measurements of material f...

Complex fluids containing long polymer chains exhibit measurably large resistance to stretching or extensional flows, due to additional stresses generated by the extensional deformation of the underlying fluid microstructure. Understanding and quantifying the response of such elastic fluids to extensional flows is necessary for optimizing fluid composition for technological applications like in...

© Appl. Rheol. 15 (2005) 390–397 Abstract: We report on the design and implementation of an evaporation blocker for cone-plate and plate-plate geometries. In addition to minimizing sample evaporation by trapping the saturated vapor inside a sample chamber, an important feature of the evaporation blocker is the suppression of solvent transport through condensation. Validation tests with DI-water...