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AKB: Biologische Physik
AKB 15: Cell Mechanics and Rheology
AKB 15.4: Vortrag
Freitag, 4. März 2005, 12:30–12:45, TU H2013
Stiff Polymers, Foams and Fibre Networks — •Claus Heussinger and Erwin Frey — Hahn-Meitner Institut, Berlin
The linear elastic properties of cellular materials like open cell foams are readily understood when considering stretching or bending compliance of a single cell. On the contrary, fibrous materials, for example the paper you most likely read this abstract from, are considerably more complicated because of the relevance of the additional scale of the fibre length lf. While stretching dominated systems remain foam-like, bending dominated networks show collective effects with a highly non-affine strain field that cannot be explained by single cell properties.
In this work we will be concerned with two-dimensional networks of stiff polymers, that differ from the purely mechanical fibres (T=0) in having an entropic stretching compliance. We show that upon addition of these thermal effects, it is the foam-like stretching dominated regime that is unstable, giving way for an intermediate asymptotic region with a non-trivial mixing of the bending and the stretching mode.
The numerical results can be explained by taking into account the whole distribution of stretching compliances of the polymer strands. In contrast to the importance of the average cell in purely enthalpic models, the polymer networks are dominated by the (fat) tails of the distribution which are of Levy-index µ=5/4.