Berlin 2015 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 64: Flow-Induced Structures in Complex Fluids (with DRG, Deutsche Rheologische Gesellschaft, and DY)
CPP 64.7: Talk
Thursday, March 19, 2015, 11:15–11:30, C 264
Foaming of polystyrene-block-poly(4-vinyl pyridine) diblock copolymers: Thermal, rheological and processing properties — Maria Schulze1, •Ulrich Alexander Handge1, Jelena Lillepärg1, Sofia Rangou1, and Volker Abetz1,2 — 1Institute of Polymer Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, 21502 Geesthacht, Germany — 2Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
Because of the high demand of polymer foams for application in the fields of lightweight construction, membrane technology, thermal and acoustic isolation the characterization of thermal and rheological properties of polymers for foam extrusion processes is of high relevance. In this study, we discuss the thermal and rheological properties of polystyrene-b-poly(4-vinyl pyridine) diblock copolymers and processing of these diblock copolymers via batch foaming. Carbon dioxide is used as blowing agent. High pressure differential calorimetry measurements reveal that the solution of carbon dioxide in these diblock copolymers leads to a decrease of the glass transition temperature of the polystyrene and the poly(4-vinyl pyridine) blocks. Furthermore rheological experiments in the oscillatory mode were carried out in order to elucidate the influence of composition and molecular weight on the flow properties. Stress-growth experiments reveal that the steady-state viscosity is characterized by a pronounced structure viscous behavior. Batch foaming experiments show that a larger molecular weight yields a lower foam density.