Levich Institute Seminar Announcement, 02/05/2008
Steinman Hall, Room #312
(Chemical Engineering Conference Room)
Dr. Allan Ye
City College of CUNY
"Pulling and Pushing - Uniaxial Extension of Polymer Solutions and Uniaxial Compression of Granular Materials"
In the first part of my talk, detailed investigation of extensional rheometry of entangled solutions of polymers with different chain architectures and polydispersity will be presented. This is motivated by the wide applications of polymers in industry such as fiber spinning, film blowing, polymer extrusion and enhanced oil recovery and coating etc. A Filament Stretching Rheometer (FSR) has been used to provide uniaxial extensional deformation on polymer samples. The experimental data on entangled polymer solutions clearly show a strong connection between the polymer structure and their rheological properties. In addition, the contributions of each component in binary blends of linear polymers indicate the importance of polydispersity in entangled systems.
For the granular materials, a uniaxial compression apparatus (DCD) has been designed with stresses being measured on three faces of the rectangular pack and the
permeability being measured in the orthogonal direction to the compressive stress (the driving force). The DCD takes a small charge of particles in a bench-top scale apparatus and employs automated
data acquisition and computer control to the hydraulic fracturing application in petroleum industry. In addition, the device allows direct visualization of the mechanical behavior of granular
assemblies during compression at network stresses. Although it is a very time-consuming process to simulate the compression of hard particles such as proppant, efforts have been made in numerical
simulation of PMMA soft particles using discrete element method (DEM). Comparison of the simulation and the experimental data from DCD is fairly well.