CHEMICAL & PETROLEUM ENGINEERING
Sachin S. Velankar, PhD
927 Benedum Hall | 3700 O’Hara Street | Pittsburgh, PA 15261
Professor Soft Materials and Rheology Group Department of Mechanical Engineering and Materials Science (Secondary) McGowan Institute for Regenerative Medicine
P: 412-624-9984 velankar@pitt.edu http://www.pitt.edu/~velankar/www
The Soft Materials and Rheology group conducts fundamental research to support the materials science of soft materials including polymers, multiphase flow, colloids, interfacial phenomena, block copolymers, thin films, and rheology. Ongoing projects include:
Capillary phenomena in Particulate Systems A sandcastle owes its strength to small menisci of water that induce attraction between the sand particles. This is a familiar example of how surface tension and wetting affect the microstructure and rheology of particulate systems. We are interested in understanding and exploiting capillary phenomena in three-phase mixtures comprising two fluid phases (often molten polymers) and one particulate species. We have constructed morphology-composition maps of such mixtures, exploited capillarity to create conductive plastics, and are now examining micromechanics of capillary forces between particles.
Diversity of bicontinuity in fluid-fluid-particle mixtures
Buckling Phenomena Slender objects readily buckle under compressive loads. We conduct research on a variety of aspects of thin film buckling including swelling induced buckling of crosslinked rubbery films, delamination of thin films, plasticity effects in thin film buckling, wrinkling and folding on viscous substrates, and the buckled topography of the luminal surface of arteries. Wrinkling and folding of thin films on a viscous liquid
Plasticity Effects in Composites Under tension, a rubber band stretches homogeneously, and then recovers its original length when released. In contrast, a strip of plastic often shows non-homogeneous strain (called “necking”), and remains deformed when released. We are examining the mechanics of rubberplastic composites, more specifically, elucidating the role of inelastic deformations. We have shown how the necking behavior of the plastic is modified by rubber, and are examining toughening mechanisms in such composites. We are also examining shape changes that appear by simply stretching and releasing such composites.
Necking and drawing of low-density polyethylene
Stretch-morphing of rubber-plastic composites
Other Research
Cocrystallization at the water/polymer interface
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We are examining the remarkable behavior of polymer-water mixtures which co-crystallize to form a hydrate. Complex material behavior (viscoelasticity, yielding, non-Newtonian rheology) is a common theme in our research. Our lab regularly assists researchers with rheological characterization of hydrogels. These include hydrogels prepared from Extracellular Matrix proteins (in collaboration with the Badylak lab at Pitt), or synthetic hydrogels used in medical or sensor applications. DEPARTMENT OF CHEMICAL AND PETROLEUM ENGINEERING
