Regensburg 2010 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 36: Poster: Nanoparticles and Composite Materials

CPP 36.7: Poster

Mittwoch, 24. März 2010, 17:30–19:00, Poster B2

Effects of strain and stress amplification in filled polymer melts — •Jan Domurath, Marina Saphiannikova, and Gert Heinrich — Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Strasse 6, 01069 Dresden

When hard filler particles are added to a polymer melt, it is usually assumed that its zero-shear viscosity and therefore the stress increase according to Einstein’s or a similar formula. In some papers one finds an alternative approach in which the local strain field is increased according to these formulas. Although both approaches provide the same increase of the shear stress in the linear limit, it is possible that the second approach violates the energy conservation law as the macroscopic and microscopic dissipated energies are not equal anymore. While for the non-linear limit it becomes even less clear whether it is the strain or the stress that is increased by the presence of filler. In this contribution we show that it is necessary to increase both the strain and the stress as originally done by Einstein [1]. As hard filler particles cannot be deformed, the polymer melt experiences a higher microscopic deformation than the macroscopic strain. To satisfy the energy conservation law, the shear stress should also be increased [1, 2]. This combined approach enables us to describe the peculiar behaviour of the overshoot peak observed recently in filled LDPE melts [3].
[1] A. Einstein. Ann. d. Phys. 19, 289 (1906), 34, 591 (1911)
[2] A. Svistkov et al. J. Appl. Mech. Tech. Phys. 50, 493 (2009)
[3] F.R. Costa et al. Adv. Polym. Sci. 210, 101 (2008)