Berlin 2005 – wissenschaftliches Programm
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AKB: Biologische Physik
AKB 100: Poster Session I
AKB 100.37: Poster
Samstag, 5. März 2005, 16:45–18:45, Poster TU D
Morphology and mechanical characteristics of cellulose fibres. In situ investigations with X-ray scattering — •Klaas Kölln1, Ingo Grotkopp1, Manfred Burghammer2, Stephan V. Roth2,3, Christian Riekel2, Sergio S. Funari3,4, Martin Dommach3,4, and Martin Müller1 — 1Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel — 2ESRF, Grenoble, Frankreich — 3HASYLAB, DESY, Hamburg — 4MPI für Kolloid- und Grenzflächenforschung, Potsdam
Tensile tests on high-oriented natural fibres of flax and ramie combined with X-ray (micro) diffraction measurements were carried out at ESRF and HASYLAB. An improvement of the orientation function of the cellulose crystals with respect to the fibre axis upon increasing strain could be observed for the high-oriented fibres (cellulose I) as well as for fibres of regenerated cellulose (cellulose II). Scanning measurements with X-ray micro diffraction showed that regions which are already highly oriented suffer only minor effects while less well oriented regions undergo a marked increase of the orientation function at the beginning of the stretching procedure. The strain of the microfibrils during a constant strain rate experiment could be measured with a time resolution of a few seconds. On the basis of a simple mechanical model, Young’s modulus of elasticity could be determined for the cellulose crystals. It is lower than values found in literature. The lateral contraction of the crystals could be observed both for cellulose I and cellulose II and Poisson ratios for these two materials were determined for the first time experimentally.