Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: POSTERS Polymer Physics

CPP 13.7: Poster

Dienstag, 24. März 2009, 14:00–16:30, P3

Micromechanics of thin films of elastomeric polypropylene — •Mechthild Franke and Robert Magerle — Chemische Physik,TU Chemnitz, Chemnitz

Elastomeric polypropylene consists of lamellar crystals embedded in an amorphous matrix. The arrangement, distribution, and connectivity of these crystals are important factors which determine the mechanical properties of the polymer. We stretch ∼ 1 µm thick films stepwise up to 100% and observe the changes in shape, orientation, and morphology of crystalline regions in situ with scanning force microscopy. We find heterogeneous deformations on length scales smaller than 2 µm. On larger length scales the deformation is homogeneous. Branching points of epitaxial grown branches on mother lamellae are very rigid and do not deform up to strains of ∼ 40%. Reversible bending of single lamellae is also observed. On stretching, some lamellae break into fragments which upon further stretching break into smaller, only 10 nm large, blocks. Less frequently, we observe strain induced melting and crystallization. Our setup allows for a number of novel experiments. For instance, cyclic loading could reveal processes on the nanometer scale leading to fatigue behavior of the specimen.