Dresden 2014 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 53: Topical session: X-ray and neutron scattering in materials science II - Atomic migration studies ranging from neutrons to coherent X-rays

MM 53.5: Talk

Thursday, April 3, 2014, 13:00–13:15, BAR 205

Mechanical properties of mesocomposite silk fibres:
viscoelasticity, structural and molecular origin — •Igor Krasnov¹, Tylo Sydle², Michael M. Koza², Manfred Burghammer³, and Martin Müller¹ — ¹Helmholtz-Zentrum, Geesthacht, Germany — ²ILL, Grenoble, France — ³ESRF, Grenoble, France

To study the response of silk to a mechanical perturbation we monitor the changes of the microscopic structure of silk as well as the molecular dynamics of the amorphous phase. In oder to achieve this goal in situ scattering experiments were performed: synchrotron radiation X-rays and cold neutrons were used as probes of the structure and dynamics, respectively. Much attention was devoted to the temporal evolution. Generally, a link between the macroscopic viscoelastic behaviour and the mechanism at the molecular length scales has been established. With our experimental techniques and analyses we could separate the mechanical properties of the crystalline region of silk from those of the amorphous part, as well as show their interplay [1]. Interesting novel results were also obtained concerning the long-time mechanical relaxation of silk and molecular diffusion processes. Both phenomena exhibit definitive memory effects and can be well described by the models based on fractional calculus. Despite the fact that these phenomena belong to very different temporal and spatial levels the fractional characteristics of these phenomena are very similar.  
[1] Krasnov I., et al. PRL 100, 048104 (2008)