Dresden 2006 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 7: SYMPOSIUM Disperse Polymer Systems I

CPP 7.7: Vortrag

Dienstag, 28. März 2006, 11:45–12:00, ZEU 160

Flow behavior of two-phase polymer blends — •Bernhard A. Wolf, Verena E. Ziegler, and Matthias Schnell — Institut für Physikalische Chemie der Johannes Gutenberg-Universität Mainz, Germany

The processing of polymer mixtures (for instance in extruders at high temperatures) is usually taking place in the heterogeneous state. Under these conditions two liquid phases (the melts of normally almost immiscible polymers) coexist and the viscosities of these mixtures are not only determined by the properties of the components, but modified considerably by the morphology of the system.

The lecture demonstrates for two binary polymer blends of different degrees of incompatibility [polyethylene oxide/poly(dimethylsiloxane) and poly(dimethylsiloxane)/poly(dimethylsiloxane-ran-methylphenylsiloxane)], how the spatial arrangement of the coexisting phases (as observed with an optical microscope during shear) influences the viscosities and the storage plus loss moduli of the mixture. Furthermore it deals with the changes resulting from the addition of compatibilizers. The measurements demonstrate that the viscosities as well as the storage moduli are normally markedly larger than predicted under the assumption of additivity of the properties of the pure components. The variations of these quantities with blend composition and with shear rate indicate under which conditions droplet/matrix structures or co-continuous morphologies are stable.