Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 20: POSTER A

CPP 20.31: Poster

Montag, 24. März 2003, 19:00–21:00, ZEU/250

Elastic, hard-elastic, rubber-like and viscous forces during drawing polyethylene — •Ke Hong and Gert Strobl — Physikalisches Institut, Universität Freiburg, Herrmann-Herder-Str.3, 79104 Freiburg, Germany

The tensile deformation behavior of various PEs was studied with the aim of an understanding of the different contributing forces. We used an INSTRON-machine equipped with a video control which maintains a constant local strain rate in the narrowest part of the specimen. In this way true stress-strain curves were obtained also for necking samples, and these show systemic changes with the sample crystallinity. Step-cycle tests provided a splitting of the strain in a recovered and an irreversible part. We observed that for oriented PE the elastic strain can be much larger than it is found in the Hookean elastic region of the initial isotropic sample. Since the associated modulus is still much higher than the shear modulus of network, we encounter here hard elasticityNo-dq. Employing stress-relaxation measurements, the viscous force included in the stress was determined. Wide angle x-ray scattering (WAXS) measurements were used to derive from the halo anisotropy the order parameter of the network chains which determines the rubber-like force.