In-Situ Visualization of Polymer Blends Processing: Influence of Viscosity Ratio and Surfaces
Kalman Migler, Erik K. Hobbie, F Qiao
We study the effects of viscosity ratio, surfaces and shear on droplet morphology in immiscible polymer blends during extrusion. These in-line experiments are performed in an optical slit die situated at the exit of a twin screw extruder. At a very high ratio of droplet to matrix viscosity, large droplets are mildly deformed by the shear stress into diamond shaped structures. As the viscosity ratio is decreased, the droplets deform into elliptical and string-like structures and can further break-up into smaller droplets. The die surface can strongly affect morphology; we have observed that droplets at the surface can breakup under conditions where they are stable in the bulk.