Berlin 2008 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 1: DRG-DPG SYMPOSIUM Rheology I
CPP 1.8: Talk
Monday, February 25, 2008, 12:00–12:15, C 130
Deformation of Inclusions and Lamellae in Melt Extension of Blends of Polystyrene and a Styrene-Butadiene Block Copolymer — •Ulrich Alexander Handge1, Matthias Buschnakowski2, and Goerg Hannes Michler2 — 1Polymer Physics, Department of Materials, ETH Zürich, CH-8093 Zürich — 2Department of Physics, Martin-Luther-University Halle-Wittenberg, D-06099 Halle/S.
The end-use properties of block copolymers depend on their composition and microstructure. Blending block copolymers with a homopolymer can lead to materials with specific end-use properties and reasonable costs. Here we studied the melt rheology of blends of a styrene-butadiene block copolymer (LN3) and polystyrene (PS 158K, BASF AG). Three blends of LN3 and PS 158K were prepared with Φ=20, 40 and 80 wt.% PS 158K. Linear viscoelastic shear oscillations and melt elongation tests were performed at 170 oC. The deformation of the blend morphology with strain was investigated using transmission electron microscopy. PS 158K and LN3 formed a two-phase blend with a PS 158K or a LN3 matrix. The block copolymer chains of LN3 were arranged in a lamellar phase. Our rheological experiments revealed that the complex modulus, the extensional viscosity and the recoverable deformation of the PS 158K/LN3 blends mainly resulted from a mixing effect of the properties of PS 158K and LN3. In melt elongation, the inclusions in the PS 158K resp. LN3 matrix were deformed into an elongated shape, and the alignment of the lamellae of the LN3 block copolymer matrix for Φ= 20% and 40% increased with strain.