Leipzig 1999 – wissenschaftliches Programm

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DRG: Deutsche Rheologische Gesellschaft

DRG 11: Strukturierte Materialien

DRG 11.2: Vortrag

Mittwoch, 3. März 1999, 09:30–09:50, HS 22

Orientation Flip of Lamellar Poly(styrene-b-isoprene) Diblock Copolymers under Extrusion — •Heike Leist¹, Kalman Geiger², and Ulrich Wiesner¹ — ¹Max-Planck-Institut für Polymerforschung, Ackermannweg 10, D-55128 Mainz — ²Institut für Kunststofftechnologie, Universität Stuttgart, Böblinger Strasse 70, D-70199 Stuttgart

The effect of oscillatory and steady shear fields to macroscopically align the microstructure of block copolymers has received significant attention in the last years. Although the conditions to obtain parallel (with unit normal of the lamellae perpendicular to both the flow and vorticity direction) as well as perpendicular (with unit normal of the lamellae perpendicular to both the flow and velocity gradient direction) lamellar orientations are well known for large amplitude oscillatory shear flow experiments it is not yet understood whether the same orientational states can be observed under extrusion. In the present contribution the lamellar orientation of a poly(styrene-b-isoprene) diblock copolymer is investigated after extrusion from a miniaturized high pressure capillary rheometer with a rectangular slit die at different apparent shear rates and temperatures using two-dimensional small angle X-ray scattering.