SBIR Phase I: A novel instrument for the determination of extensional rheology

This Small Business Innovation Research (SBIR) Phase I project describes a unique instrument capable of quantifying the extensional rheological behavior of solutions, pastes and melts. In this instrument a small quantity of fluid is rapidly stretched between two plates to form a liquid bridge, and the diameter decrease is subsequently monitored as the fluid drains under gravity and surface tension. Comparison of rheological models with the data allows one to extract viscosity, surface tension, elasticity and other parameters relating to extensional flows. Currently, researchers rely purely on simple shear characterization or capillary rheometry, neither of which can provide unambiguous quantitative information about extensional flow behavior. The integration of hardware and analysis software will make the instrument both versatile and unique. The instrument will be invaluable to industry where all processing flows (such as extrusion, filling, pumping, blow molding, spraying etc.) involve extensional flow fields. It will find utility in industry as both a quality control tool and a research grade device. Additionally it will be of use to academia, where no simple quantitative analytical device exists for examining the draining (and filament forming) behavior of fluids. In addition the instrument described has a number of intrinsic advantages that make it ideal for a shop floor installation. It is compact (our envisioned design will have a footprint smaller than 0.1 m 2 ) and robust (with few moving parts it will be tolerant of dust and vibration). It should also be easy to use, especially in an indexing mode for intra-lab comparisons (or floor level quality control). The removable plates will allow easy cleaning and the ability to change plate surface chemistry. Finally the sample volumes will be small.