THE EFFECT OF FLOW-INDUCED ORIENTATION ON THE RHEOLOGY OF CARBON NANOFIBER/POLYSTYRENE COMPOSITES DURING FLOW REVERSAL EXPERIMENTS
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Chemical and Biomolecular Engineering Honors Theses; 2011
The effects of carbon nanofiber orientation and flow history on the subsequent shear rheology of polystyrene/carbon nanofiber composites were studied using experimental measurements and constitutive modeling. Results from flow reversal experiments show that the pre-orientation of carbon nanofibers has a significant effect on the transient shear behavior, specifically on the characteristic stress overshoot. The mass fraction of carbon nanofibers has a significant effect on the rheology when the fibers are initially randomly oriented, but not necessarily when there is pre-orientation in the flow direction. In addition, the initial composite stress, controlled by using variable rest times between flow reversals, has a significant effect on the observed transient behavior. Experimental results are compared with a microstructurally-based constitutive model designed to predict the flow behavior and carbon nanofiber orientation. It is demonstrated that the model predicts the effects of particle orientation and flow history during flow reversal experiments.
OSU College of Engineering - Undergraduate Research Scholarship
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