Dresden 2006 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 7: SYMPOSIUM Disperse Polymer Systems I

CPP 7.4: Vortrag

Dienstag, 28. März 2006, 10:30–10:45, ZEU 160

Linear viscoelastic shear oscillation investigations of melt mixed blends of polycarbonate with multiwalled carbon nanotubes and polyethylene — •Petra Pötschke and Mahmoud Abdel-Goad — Leibniz Institute of Polymer Research Dresden, Hohe Strasse 6, 01069 Dresden, Germany

The concept of double percolation was adapted to melt mixed blends of a conductive polycarbonate composite containing 2 wt% multiwalled carbon nanotubes (PC-2NT) and polyethylene (PE). The blends were melt mixed using a small scale twin-screw compounder over the whole composition range. This study presents linear viscoelastic shear oscillation tests on these blends performed at 280^∘C. We investigated the question, if melt rheological measurements are able to detect the co-continuous composition range in such systems unequivocally. The percolation of the nanotubes in PC is clearly detected by an increase in complex viscosity by lowering oscillation frequency and the formation of a plateau of G’ at low frequencies. Viscosity and moduli of the selected high density PE are higher than those of PC-2NT which gives favourable conditions for the formation of a continuous PC-2NT phase at low concentrations. Whereas all blends show values of G” between those of the parent materials, some of the composites in the middle concentration range exceed the parent values of G’ and complex viscosity, especially at low frequencies. It was found from morphological studies and selective extraction experiments that the co-continuous structure formation starts at 20 vol% PC-2NT. At this composition, we also find maximum values of G’, G” and complex viscosity over the whole frequency range.