| Abstract: | Suspensions, which are filled at loading levels approaching their maximum packing fractions, present special processing challenges. The flow and deformation behavior of such highly filled suspensions are dominated by strong slip effects. Furthermore, during pressure driven flows of these suspensions, the polymer matrix can filter out, giving rise to demixing and unstable flows. In this study, the capillary flow and extrusion of highly filled suspensions of ammonium sulfate and other salt fillers in a poly(butadiene acrylonitrile acrylic acid), PBAN matrix were investigated. The experimentally observed instabilities were elucidated in conjunction with a proposed mechanism, involving slip and filtration rates. This mechanism suggested greater affinity to unstable flows with relatively lower matrix shear viscosity, greater particle size of the filler, and greater convergence ratio; all of which were experimentally verified. |
